Inverted pendulum type vehicle

ABSTRACT

An inverted pendulum type vehicle includes a vehicle body frame; a main wheel including a plurality of rotatable driven rollers arranged to form a ring, and a pair of left and right driving disks supported for rotation on the vehicle body frame. Each of the driving disks includes a plurality of rotatable driving rollers, disposed for contact in a twisted relationship with the driven rollers. The vehicle also includes a pair of left and right driven pulleys provided on outer sides of the driving disks, and a pair of left and right driving units, attached to the vehicle body frame above the main wheel, and including motors having output power shafts to which driving pulleys are attached. Endless transmission members interconnect the driving pulleys and the driven pulleys. The left and right driving units are disposed in an vertically offset relationship from each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority under 35 USC 119 based on Japanesepatent applications Nos. 2012-111054, filed on May 14, 2012, and2012-111059, filed on May 14, 2012. The entire subject matter of each ofthese priority documents, including specification claims and drawingsthereof, is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an inverted pendulum type vehicle, andmore particularly to an inverted pendulum type vehicle wherein left andright driving disks disposed at the opposite left and right ends of amain wheel are driven to rotate by corresponding individual drivingunits.

2. Description of the Background Art

Conventionally, as an inverted pendulum type vehicle, for example, aninverted pendulum type vehicle is known which includes a vehicle bodyframe, a main wheel, a pair of left and right driving disks, and drivingunits (see, for example, Patent Documents 1 and 2). The main wheel isconfigured by combining a plurality of rotatable driven rollers in sucha manner that axial lines of rotation of the driven rollers form a ring.The left and right driving disks are supported for rotation on thevehicle body frame and positioned on the opposite sides of the mainwheel in a substantially coaxial relationship with an axial line ofrotation of the main wheel. Each of the left and right driving disksincludes a plurality of rotatable driving rollers disposed for contactin a twisted relationship with the driven rollers. The driving unitsrespectively drive the left and right driving disks independently ofeach other.

The driving units include a left side driving unit for driving the leftside driving disk, and a separate right side driving unit for drivingthe right side driving disk. Each of the left and right side drivingunits includes a driving motor attached to the vehicle body frame at aposition above the main wheel, and a driving pulley attached to anoutput power shaft of the electric motor. Each of the left and rightside driving units further includes a driven pulley attached to acorresponding one of the left and right driving disks, and an endlesstransmission belt extending between and around the mutuallycorresponding driving pulley and driven pulley.

-   [Patent Document 1]—Japanese Patent Laid-Open No. 2010-247640-   [Patent document 2]—Japanese Patent Laid-Open No. 2011-63242

Problem to be Solved by the Invention

It is demanded to increase the driving torque of the driving disks inorder to improve the traveling performance of the inverted pendulum typevehicle. As a countermeasure for increasing the driving torque, it seemsrecommendable to use an electric motor of an increased size to useincreased output torque of the driving motor or to raise the reductionratio between the electric motor and the driving disks.

However, in a conventional inverted pendulum type vehicle, the electricmotor of the left side driving unit and the electric motor of the rightside driving unit are disposed in a juxtaposed relationship with eachother in a vehicle body widthwise direction at the same height on thevehicle. Therefore, increase of the size of the electric motor isrestricted by a space, and in order to use an electric motor of anincreased size, it is necessary to increase the vehicle body width.Further, in a power transmission mechanism configured from a drivingpulley, a driven pulley and an endless transmission belt, the reductionratio depends upon the pulley size ratio between the driving pulley andthe driven pulley, and there is a limitation to increase of thereduction ratio.

In contrast, it seems recommendable to add a new gear type reductiongear to the electric motor. However, it is difficult in terms of thespace to add a new reduction gear to the electric motor, and it isnecessary to increase the size of the vehicle body.

Further, if it is attempted to prepare a plurality of types of invertedpendulum type vehicles having output torque different depending upon thephysique of the occupant such as a model on which a small person is toride or another model on which a large person is to ride, then theconventional inverted pendulum type vehicle is not suitable. Inparticular, in the conventional inverted pendulum type vehicle, theelectric motor of the left side driving unit and the electric motor ofthe right side driving unit are disposed in a juxtaposed and alignedrelationship with each other in the vehicle body widthwise direction atthe same height on the vehicle, as described above. Therefore, a spacenecessary for the change to an electric motor of different outputtorque, particularly, a space in the vehicle body widthwise direction,cannot be assured. Consequently, a plurality of inverted pendulum typevehicles of different vehicle classifications must be prepared, whereinthe vehicle body frame is changed in response to the output torque ofthe electric motor.

SUMMARY OF THE INVENTION

An object of the present invention is to make it possible to increasethe output torque of driving disks while retaining a compact vehiclebody configuration, without changing the vehicle classification.

Another object of the present invention is to apply appropriate initialtension to an endless transmission belt used in a driving unit of aninverted pendulum type vehicle.

Throughout the present specification, reference numbers are used torefer to the exemplary structures shown in the drawings, and suchnumbers are intended to illustrate, rather than to limit the invention.

According to a first aspect of the present invention, there is providedan inverted pendulum type vehicle including: a vehicle body frame (10);a main wheel (52) formed by combining a plurality of rotatable drivenrollers (64) such that axial lines of rotation of the driven rollers(64) form a ring; left and right driving disks (58) supported forrotation on the vehicle body frame (10) in such a manner as to bepositioned on the left and right sides of the vehicle body frame (10) ina substantially coaxial relationship with an axial line of rotation ofthe main wheel (52) and each including a plurality of rotatable drivingrollers (66) disposed for contact in a twisted relationship with thedriven rollers (64).

The vehicle also includes left and right driven pulleys (60) providedcoaxially on the vehicle body outer sides of the driving disks (58);driving units (90, 130) attached to the vehicle body frame (10) abovethe main wheel (52) and having output power shafts (98, 138) to whichdriving pulleys (100, 140) are attached; and endless transmissionmembers (122, 144) extending between and around mutually correspondingones of the driving pulleys and the driven pulleys (60), wherein theleft and right driving units (90, 130) are disposed in an verticallyoffset relationship from each other.

According to a second aspect of the present invention, there is providedan inverted pendulum type vehicle wherein the left and right drivingunits (90, 130) overlap at least at part thereof with each other asviewed in plan.

According to a third aspect of the present invention, there is providedan inverted pendulum type vehicle wherein each of the driving units (90,130) has an electric motor (84, 132), a reduction gear (96, 136)disposed between the corresponding one of the output power shafts (98,138) and the electric motor (84, 132).

According to a fourth aspect of the present invention, there is providedan inverted pendulum type vehicle wherein the electric motor (84, 132)of each of the driving units (90, 130) is disposed at a positiondisplaced to the side on which the corresponding one of the reductiongears (96, 136) is not disposed with respect to a center line in thevehicle widthwise direction, and the electric motor (84) of the drivingunit (90) disposed on the upper stage is positioned just above thereduction gear (136) of the driving unit (130) disposed on the lowerstage, while the reduction gear (96) of the driving unit (90) disposedon the upper stage is positioned just above the electric motor (132) ofthe driving unit (130) disposed on the lower stage.

According to a fifth aspect of the present invention, there is providedan inverted pendulum type vehicle wherein each of the reduction gears(96, 136) has a portion projecting sidewardly with respect to the centeraxial line of the corresponding one of the electric motors (84, 132),and the projecting portions (102A, 142A) of the reduction gears (96,136) are disposed so as to project in different directions from eachother between the left and right driving units (90, 130).

According to a sixth aspect of the present invention, there is providedan inverted pendulum type vehicle wherein the vehicle body frame (10)has a pair of left and right attachment plates (22, 24) disposed inparallel to each other on the opposite sides of the vehicle body, andthe driving units (90, 130) are fixed at portions thereof which neighborwith the output power shafts (98, 138) while openings or cutawayportions (22B, 24B) through which the output power shafts (98, 138)extend are formed in the attachment plates (22, 24), respectively.

According to a seventh aspect of the present invention, there isprovided an inverted pendulum type vehicle which has: a vehicle bodyframe (10); a main wheel (52) formed by combining a plurality ofrotatable driven rollers (64) such that axial lines of rotation of thedriven rollers (64) form a ring; left and right driving disks (58)supported for rotation on the vehicle body frame (10) in such a manneras to be positioned on the opposite left and right sides of the vehiclebody frame (10) in a substantially coaxial relationship with an axialline of rotation of the main wheel (52) and each including a pluralityof rotatable driving rollers (66) disposed for contact in a twistedrelationship with the driven rollers (64); left and right driven pulleys(60) provided coaxially on the vehicle body outer sides of the drivingdisks (58); driving units (90, 130) attached to the vehicle body frame(10) above the main wheel (52) and having output power shafts (98, 138)to which driving pulleys (100, 140) are attached; and endlesstransmission members (122, 144) extending between and around mutuallycorresponding ones of the driving pulleys (100, 140) and the drivenpulleys (60), wherein the inverted pendulum type vehicle has adjustmentmeans for attaching the left and right driving units (90, 130) to thevehicle body frame (10) such that fixing positions of the left and rightdriving units (90, 130) in the upward and downward direction can bechanged.

According to an eighth aspect of the present invention, there isprovided an inverted pendulum type vehicle wherein the inverted pendulumtype vehicle has adjustment bolts (124, 146) attached for rotation tothe vehicle body frame (10) and screwed with an upper portion of thedriving units (90, 130), and the driving units (90, 130) are moved inthe upward and downward directions with respect to the vehicle bodyframe by adjustment of the screwed amount of the adjustment bolts (124,146).

According to a ninth aspect of the present invention, there is providedan inverted pendulum type vehicle wherein attachment plates (22, 24) areattached to the vehicle body frame (10) sidewardly of the vehicle bodyand bolt penetrating holes (22A, 24A) each in the form of an elongatedhole elongated in the upward and downward direction are formed in theattachment plates (22, 24), and the driving units (90, 130) are fixed tothe vehicle body frame (10) by mounting bolts (26, 28) which extendthrough the bolt penetrating holes (22A, 24A) and held in threadedengagement with the driving units (90, 130).

According to a tenth aspect of the present invention, there is providedan inverted pendulum type vehicle wherein openings or cutaway portions(22B, 24B) through which the output power shafts (98, 138) extend areformed in the attachment plates (22, 24), respectively.

According to an eleventh aspect of the present invention, there isprovided an inverted pendulum type vehicle wherein the attachment plate(22, 24) of the left side driving unit (90) and the attachment plate(22, 24) of the right side driving unit (130) are attached to the sidesof the vehicle body opposite to each other.

According to a twelfth aspect of the present invention, there isprovided an inverted pendulum type vehicle wherein the left and rightdriving units (90, 130) are disposed in an offset relationship from eachother on two upper and lower stages and an upper frame (14D, 14E) of thevehicle body frame (10), to which the driving unit (130) on the lowerstage is attached, is positioned below the driving unit (90) on theupper stage, and a space (149) into which a tool (T) or a jig forrotating the adjustment bolt (146) can be advanced is assured betweenthe upper frame (14D) and a bottom portion of the driving unit (90) onthe upper stage even if the driving unit (90) on the upper stage ispositioned at a most downwardly moved position.

According to a thirteenth aspect of the present invention, there isprovided an inverted pendulum type vehicle wherein each of the left andright driving units (90, 130) is configured from an electric motor (84,132) and a reduction gear (96, 136), and the reduction gears (96, 136)are fixed to the attachment plates (22, 24) while the electric motors(84, 132) are positioned on the open side.

According to the first aspect of the present invention, in comparisonwith a case in which the left and right driving units (90, 130) aredisposed in a juxtaposed relationship in the vehicle widthwise directionat the same height on the vehicle, a greater disposition space in thevehicle widthwise direction can be taken for each of the driving units(90, 130) in the same vehicle body width. Consequently, increasing thetorque of the driving units, and addition of the reduction gears becomepossible without increasing the vehicle body width. Further, the drivingunits (90, 130) having output power torque ready for a model ofdifferent driving torque can be disposed suitably without changing thevehicle classification.

According to the second aspect of the present invention, in comparisonwith the case in which the left and right driving units (90, 130) aredisposed in a juxtaposed relationship in the vehicle widthwise directionat the same height on the vehicle, upsizing (increase in torque) of theindividual driving units (90, 130) can be carried out with the samevehicle body width.

According to the third aspect of the present invention, since an openingis provided at the disposition portions of the driving units (90, 130),the new reduction gears (96, 136) are added, and the driving torque ofthe driving disks (58) increases by speed reduction by the new reductiongears.

According to the fourth aspect of the present invention, the weightbalance between the left and the right of the vehicle body frame isimproved, and since the electric motors (84, 132) which are heat sourcesare disposed in a spaced relationship from each other, heat damage byadjacent disposition of the heat source portions to each other can beavoided.

According to the fifth aspect of the present invention, effective use ofspace and balancing of weight between the front and the rear of thevehicle body can be carried out.

According to the sixth aspect of the present invention, the powertransmission sections including the driving pulleys (100, 140) aresupported more firmly by the attachment plates (22, 24), and therigidity of the vehicle body frame (10) is enhanced by the attachmentplates (22, 24) and the supporting rigidity of the power transmissionsections is raised.

According to the seventh aspect of the present invention, if the fixingpositions of the driving units (90, 130) themselves in the upward anddownward direction to the vehicle body frame (10) are changed, then thespacing distance between the driving pulleys (100, 140) and the drivenpulleys (60) changes. Consequently, initial tension is applied to theendless transmission members (122, 144) without the necessity forprovision of tension application means such as a tension roller.

According to the eighth aspect of the present invention, the initialtension to be applied to the endless transmission members (122, 146) canbe adjusted quantitatively by adjustment of the screwed amount of theadjustment bolts (124, 146).

According to the ninth aspect of the present invention, the drivingunits (90, 130) can be attached to the vehicle body frame (10) by asimple attachment structure such that the fixing positions thereof inthe upward and downward direction can be changed.

According to the tenth aspect of the present invention, the side of theendless transmission members (122, 144) to which the initial tension isapplied including the driving pulleys (100, 140) is supported morefirmly by the attachment plates (22, 24). Further, the rigidity of thevehicle body frame (10) is improved by the attachment plates (22, 24)and the supporting rigidity of the power transmission sections isenhanced.

According to the eleventh aspect of the present invention, the left andright driving units (90, 130) can be supported individually with highrigidity by the disposition of the attachment plates (22, 24).

According to the twelfth aspect of the present invention, even if theleft and right driving units (90, 130) are disposed on the two upper andlower stages relative to each other, adjustment of the position of thedriving unit (130) on the lower stage in the upward and downwarddirection can be carried out. An upper frame of the vehicle body frame(10) to which the driving unit (130) on the lower stage is attachedserves as a lower frame of the vehicle body frame (10) to which thedriving unit (90) on the upper stage is attached. The driving units (90,130) can be accessed through the space, in which the driving unit (90)on the upper stage is accommodated, from the side on which theattachment plate (22) is not provided. In short, since the driving sideof the driving unit (130) on the lower stage becomes the open side ofthe upper space, the adjustment bolts (124, 146) of the driving units(90, 130) on the upper stage and the lower stage can be accessed fromthe same side without being obstructed by the endless transmissionmember (122).

According to the thirteenth aspect of the present invention, since theelectric motors (84, 132) are positioned on the open side, a harness andso forth can be wired readily and besides the electric motors (84, 132)can be connected simply.

For a more complete understanding of the present invention, the readeris referred to the following detailed description section, which shouldbe read in conjunction with the accompanying drawings. Throughout thefollowing detailed description and in the drawings, like numbers referto like parts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of an embodiment of an invertedpendulum type vehicle according to the present invention.

FIG. 2 is a front elevational view of the inverted pendulum type vehicleaccording to the present embodiment.

FIG. 3 is a perspective view of the inverted pendulum type vehicleaccording to the present embodiment.

FIG. 4 is a perspective view of a vehicle body frame used in theinverted pendulum type vehicle according to the present embodiment.

FIG. 5 is a side elevational view, partly in section, of a seatsupporting section of the inverted pendulum type vehicle according tothe present embodiment.

FIG. 6 is a front elevational view selectively showing a traveling unitand a driving unit of the inverted pendulum type vehicle according tothe present embodiment.

FIG. 7 is a front elevational view selectively showing the travelingunit and the driving unit of the inverted pendulum type vehicleaccording to the present embodiment and showing the traveling unit in asectional view.

FIG. 8 is an enlarged sectional view of an axle supporting section ofthe inverted pendulum type vehicle according to the present embodiment.

FIG. 9 is a side elevational view selectively showing the traveling unitand the driving unit of the inverted pendulum type vehicle according tothe present embodiment and showing the traveling unit in a sectionalview.

FIG. 10 is a sectional view of a reduction gear used in the driving unitof the inverted pendulum type vehicle according to the presentembodiment.

FIG. 11 is a lower side perspective view showing a lifting mechanism fora seat.

FIG. 12 is a plan view showing the lifting mechanism for a seat.

FIG. 13 is an upper side perspective view showing the lifting mechanismfor a seat which is at a lowered position.

FIG. 14 is an upper side perspective view showing the lifting mechanismfor a seat which is at a raised position.

FIG. 15 is a partial exploded perspective view of the seat.

FIG. 16 is an upper side perspective view illustrating a state in whicha lid of a battery case is open.

FIG. 17 is a side elevational view of the inverted pendulum type vehiclein a rearwardly inclined state.

FIG. 18 is a partial side elevational view showing a modification to theseat.

FIG. 19 is a front elevational view selectively showing a traveling unitand a driving unit of an inverted pendulum type vehicle according toanother embodiment.

DETAILED DESCRIPTION

In the following, an embodiment of an inverted pendulum type vehicle ofthe present invention is described with reference to the drawings. Inthe following description, directions are defined with reference to anoccupant seated on the inverted pendulum type vehicle.

The inverted pendulum type vehicle 1 includes a traveling unit 50 whichconfigures a wheel, a left side driving unit 90 and a right side drivingunit 130 for driving the traveling unit 50, and an electrical unit 300for controlling the left side driving unit 90 and the right side drivingunit 130. The inverted pendulum type vehicle 1 further includes abattery pack 250 for supplying electric power to the electrical unit300, and a seat unit 170 on which an occupant is to be seated. Thetraveling unit 50, left side driving unit 90, right side driving unit130, electrical unit 300, battery pack 250 and seat unit 170 aresupported on a vehicle body frame 10 which configures a vehicle bodyskeleton.

(Vehicle Body Frame)

As shown in FIG. 4, the vehicle body frame 10 is formed by welding aplurality of bent pipe members to each other. The pipe members may becircular pipes made of steel or aluminum. The vehicle body frame 10includes a traveling unit supporting section 12 for supporting thetraveling unit, and a driving unit supporting section 14 connected to anupper portion of the traveling unit supporting section 12 and supportingthe driving unit thereon. The vehicle body frame 10 further includes abattery supporting section 16 connected to a rear portion of thetraveling unit supporting section 12 and supporting the battery pack 250thereon.

The vehicle body frame 10 includes a center post (lifting apparatussupporting member) 44 in the form of a pipe member which extendsupwardly and downwardly and is open at the opposite upper and lower endsthereof. The center post 44 is connected to an upper portion of thetraveling unit supporting section 12. A pair of U-shaped slits areformed at a lower end of the center post 44 such that they extendthrough the center post 44 in the leftward and rightward direction andcontinue to the lower end face of the center post 44. The traveling unitsupporting section 12 is formed by bending a pipe member in an annularsaddle shape and is received at rear end portions thereof in and weldedto the slits.

The traveling unit supporting section 12 has a front edge portion 12Aand a rear edge portion 12B in pair in the forward and backwarddirection extending in the leftward and rightward direction. Thetraveling unit supporting section 12 further has a pair of left andright side portions 12C of a substantially U shape which have left endsand right ends connecting to the left ends and the right ends,respectively, of the front edge portion and the rear edge portion andproject, at central portions thereof, to the outer sides in thewidthwise direction and extend downwardly. The traveling unit supportingsection 12 is joined at the rear edge portion 12B thereof to the centerpost 44. A pair of left and right gussets 46 of a substantiallytriangular shape are joined to the joining portion between the rear edgeportion 12B and the center post 44 to reinforce the joining portion.

Left and right step supporting pipes 36 are coupled to lower portions ofthe left and right side portions 12C and extend downwardly. A pair ofstep attachment plates 38 are coupled to the front side of the left andright step supporting pipes 36 and extend forwardly such that facesthereof are directed leftwardly and rightwardly. A pair of steps 40 forsupporting the sole of the feet of the occupant are provided in aprojecting manner on outer faces of the left and right step attachmentplates 38 in the vehicle widthwise direction.

A pair of plate-shaped axle supporting plates 20 are joined to lowerportions of the left and right side portions 12C such that they extenddownwardly and have faces directed leftwardly and rightwardly. The axlesupporting plates 20 are coupled at a front edge thereof to a rearportion of the step supporting pipes 36. A bearing recessed portion 20Ais formed in each of the left and right axle supporting plates 20 suchthat it extends through the axle supporting plate 20 in the leftward andrightward direction and is open downwardly.

The driving unit supporting section 14 is formed by disposing aplurality of pipes including the center post 44 in a cage shape and isprovided immediately above the traveling unit supporting section 12. Thedriving unit supporting section 14 has a first pipe 14A and a secondpipe 14B. The first pipe 14A extends obliquely upwardly rearwardly froma right end portion of the front edge portion 12A of the traveling unitsupporting section 12, extends upwardly in a curved state, is bent andthen extends rearwardly, is curved and extends downwardly leftwardly andis joined to an outer face at an intermediate portion of the center post44 in the upward and downward direction.

The second pipe 14B extends obliquely upwardly rearwardly from a leftend portion of the front edge portion of the traveling unit supportingsection 12, is bent and extends upwardly, and is further bent andextends rearwardly to form a free end.

A pair of third pipes 14C are joined at a front end thereof to a lowerend portion of the first pipe 14A and the second pipe 14B which extendrearwardly upwardly in an inclined relationship. The third pipes 14Cindividually extend in the forward and backward direction and are joinedat a rear end thereof to the rear edge portion 12B of the traveling unitsupporting section 12. A fourth pipe 14D is coupled at a front endthereof to an intermediate portion of the portion of the first pipe 14Awhich extends upwardly. The fourth pipe 14D extends rearwardly, is bentand extends downwardly and is joined at a rear end thereof to the rightside third pipe 14C. A fifth pipe 14E is joined at a front end thereofto an intermediate portion of the portion of the second pipe 14B whichextends upwardly. The fifth pipe 14E extends rearwardly, is bent so asto extend rearwardly upwardly, is further bent so as to extendrightwardly and is joined to an outer face of an intermediate portion ofthe center post 44. The portion of the first pipe 14A which extendsforwardly and backwardly at an upper portion thereof and an upper endportion of the second pipe 14B are joined together by a sixth pipe 14Fwhich extends horizontally in the leftward and rightward direction.

The portion of the fourth pipe 14D which extends forwardly andbackwardly and the portion of the fifth pipe 14E which extends forwardlyand backwardly are joined together by a seventh pipe 14G which extendshorizontally in the leftward and rightward direction. The portions ofthe first pipe 14A and the second pipe 14B which extend upwardly arejoined together by a connection plate 14H which extends in the leftwardand rightward direction. By connecting a portion of the driving unitsupporting section 14 (first pipe 14A, fifth pipe 14E) to anintermediate portion (or an upper portion) of the center post 44, a seat200 movable in the upward and downward directions can be supportedstably. It is to be noted that a similar effect can be obtained also bya configuration wherein a portion of the battery supporting section 16is connected to an intermediate portion (or an upper portion) of thecenter post 44.

The driving unit supporting section 14 has a cage shape having two upperand lower stages having a substantially cubic upper side cage portion141 and a lower side cage portion 14J. The upper side cage portion 141is disposed upwardly with respect to the driving unit supporting section14 while the lower side cage portion 14J is disposed downwardly withrespect to the driving unit supporting section 14 across the boundaryprovided by the seventh pipe 14G. The upper side cage portion 141 has aframe (left side frame-shaped portion) which forms a left side portionof the upper side cage portion 141 defined by an upper half portion ofthe second pipe 14B and the fifth pipe 14E, and a left side driving unitattachment plate 22 which is a plate-shaped gusset is coupled to theframe of the upper side cage portion 141. The lower side cage portion14J has a frame (right side frame-shaped portion) which forms a rightside portion of the lower side cage portion 14J defined by a lower halfportion of the first pipe 14A, the third pipe 14C on the right side andfourth pipe 14D, and a right side driving unit attachment plate 24 whichis a plate-shaped gusset is coupled to the frame of the lower side cageportion 14J. The left side driving unit attachment plate 22 and theright side driving unit attachment plate 24 are disposed in anvertically offset state and in parallel to each other on the outer sidesin the vehicle body widthwise direction.

The battery supporting section 16 is formed from a pipe disposed in achannel shape open forwardly as viewed in plan, and is jointed at leftand right end portions thereof to rear portions of the side portions 12Cof the traveling unit supporting section 12. A shelf board 17 in theform of a flat plate is provided on the inner side of the channel shapeof the battery supporting section 16. The battery supporting section 16and the shelf board 17 exhibit a shelf shape protruding rearwardly withrespect to the traveling unit supporting section 12. To a rear portionof each the side portions 12C of the traveling unit supporting section12, a reinforcement pipe 30 formed in a U shape (semicircular shape) isjoined at the opposite ends thereof. In other words, The U-shapedreinforcement pipe 30 is provided in a projecting manner at a rearportion of the side portion 12C of the traveling unit supporting section12. An upper portion of the left and right reinforcement pipes 30 and alower portion of the opposite left and right portions of the batterysupporting section 16 are joined together by a pair of left and rightlinear brace pipes 32. The brace pipes 32 serve as braces to reinforcethe battery supporting section 16.

The vehicle body frame 10 including the traveling unit supportingsection 12, driving unit supporting section 14 and battery supportingsection 16 is covered with an outer shell 18 made of a synthetic resinand indicated by imaginary lines in FIG. 1.

(Traveling Unit)

The traveling unit 50 is disposed between the left and right sideportions 12C of the traveling unit supporting section 12. As shown inFIGS. 1 to 3, 6 and 7, the traveling unit 50 includes a hollow axle 54extending horizontally in the vehicle widthwise direction (leftward andrightward direction), and left and right driving disks 58 supported forrotation independently of each other on an outer periphery of the hollowaxle 54. The traveling unit 50 further includes an annular main wheel 52penetrated by the hollow axle 54 and disposed between the left and rightdriving disks 58, and left and right driven pulleys 60 for a cog beltfastened to the left and right driving disks 58 by bolts 59. The leftand right driving disks 58 and the left and right driven pulleys 60 aredisposed on the same axial line with a central axial line of the hollowaxle 54 as a common axial line. As shown in FIG. 8, a columnar pulleyattaching shaft portion 58C is provided in a projecting manner at thecenter of an outer face of each of the driving disks 58 in the vehiclewidthwise direction, and an axial through-hole 60A is formed in each ofthe driven pulleys 60. The driven pulley 60 is fixed to the outer sideface of the driving disk 58 in the vehicle widthwise direction by thebolts 59 in a state in which the pulley attaching shaft portion 58C isinserted in the axial through-hole 60A.

The main wheel 52 is a driving wheel which is driven based on invertedpendulum control and is configured, as shown in FIG. 7, from a circularring member 62 made of metal, and a plurality of driven rollers (freerollers) 64 attached to an outer periphery of the circular ring member62. The main wheel 52 contacts with the ground at the driven rollers 64thereof. Each of the driven rollers 64 is configured from a cylindricalmetal base portion 64A mounted for rotation on the outer periphery ofthe circular ring member 62 and a cylindrical rubber outer peripheralportion 64B of vulcanized rubber adhered to an outer periphery of themetal base portion 64A. A plurality of driven rollers 64 are provided inthe ring direction (circumferential direction) of the circular ringmember 62 and can individually rotate (rotate) around a tangential lineto the circular ring member 62 at the disposition position of the drivenrollers 64 themselves. In short, the main wheel 52 is configured bycombining the plural driven rollers 64, which can rotate independentlyof each other, such that they form a ring. Strictly speaking, the pluraldriven rollers 64 are combined so as to form a polygon having a numberof angles corresponding to the number of driven rollers 64 thereby toform the main wheel 52.

The left and right driving disks 58 have a disk shape of an outerdiameter smaller than a central radius of the circular ring member 62,and an outer peripheral portion thereof is a conical outer peripheralportion 58D which has a substantially truncated conical shape. Aplurality of driving rollers 66 made of metal are supported for rotationat equal distances in the circumferential direction on the conical outerperipheral portion 58D. The driving rollers 66 of the left side drivingdisk 58 and the driving rollers 66 of the right side driving disk 58 aredisposed in a leftwardly and rightwardly symmetrical relationship witheach other, and the centers of the driving rollers 66 are disposed in atwisted relationship with the center of rotation of the driving disk 58.Consequently, the left and right driving rollers 66 have leftwardly andrightwardly symmetrical shapes and have an inclined disposition similarto teeth of a helical gear wheel.

The hollow axle 54 supports the left and right driving disks 58 forrotation independently of each other through two pairs of ball bearings(radial ball bearings) 56. The ball bearings 56 are disposed in a spacedrelationship from each other in the direction of the axial line of thehollow axle 54 on an outer periphery of the hollow axle 54. As shown inFIG. 8, the left and right driving disks 58 have an axial through-holes58A. Increased diameter portions 58B which are increased in diameter inan offset state are formed at opening ends of the axial through-holes58A on the opposite sides in the direction of the axial line. A collarmember 57 is fitted on an outer periphery of the hollow axle 54, and thetwo ball bearings 56 are fitted at the inner race thereof on the hollowaxle 54 in such a manner as to sandwich the collar member 57therebetween and fitted at the outer race thereof with the increaseddiameter portions 58B. The two ball bearings 56 abut at an end face ofthe outer race thereof with positioning stepped portions 58E formed atend portions of the increased diameter portions 58B and abut at an endface of the inner race thereof with the collar member 57 such that theyare positioned in the direction of the axial line and disposed in aspaced relationship from each other. It is to be noted that the axiallength of the collar member 57 and the dimension by which thepositioning stepped portions 58E formed in pair on the opposite sides ofthe axial through-holes 58A of the axial through-holes 58A in thedirection of the axial line are equal to each other.

A pair of positioning stepped portions 54A are formed in a spacedrelationship by a predetermined distance from each other in thedirection of the axial line on the outer periphery of the hollow axle 54by reducing the diameter on the end portion sides of the hollow axle 54.The distance between the left and right driving disks 58 in thedirection of the axial line is set by abutment of an end face of theinner race of the ball bearing 56 on the inner side in the direction ofthe axial line from between the two ball bearings 56 with thepositioning stepped portion 54A.

A nut 68 is screwed with each of male threaded portions 54B formed inthe proximity of left and right end portions of the hollow axle 54. Bytightening of the nut 68, a ring-shaped protrusion 68A formed on theinner diameter side of the nut 68 presses an end face of the inner raceof the ball bearing 56 on the outer side in the direction of the axialline from between the two ball bearings 56. Consequently, the innerraces of the two ball bearings 56 and the collar member 57 aresandwiched by the positioning stepped portion 54A and the nut 68 andpositioned in the direction of the axial line of the driving disk 58with respect to the hollow axle 54. Consequently, the driving disk 58 issupported for rotation by a supporting structure of low frictionalresistance.

The outer diameter of the nut 68 (flange outer diameter) is formedgreater than the outer diameter of the outer race of the ball bearing56. In short, the outer diameter of the nut 68 is formed greater thanthe inner diameter of the axial through-hole 58A of the driving disk 58.Consequently, The disposition position of the ball bearing 56 is hiddenby the nut 68 thereby to form a labyrinth seal so that dust becomes lesslikely to enter the ball bearing 56.

Meanwhile, the axial through-hole 60A of the driven pulley 60 is formedgreater than the outer diameter of the nut 68. In short, the axialthrough-hole 60A has an inner diameter which allows the nut 68 to extendthrough the axial through-hole 60A in the direction of the axial line.Consequently, in a state in which the nut 68 is screwed with the hollowaxle, the driven pulley 60 can be mounted on and removed from thedriving disk 58.

The left and right driving disks 58 assembled to the hollow axle 54 insuch a manner as described above are supported on a substantially sameaxial line (concentrically) in such a manner that the main wheel 52 issandwiched from the opposite left and right sides by the ring-shapedroller train groups by the left and right driving rollers 66 as shown inFIGS. 2 and 6. Consequently, the main wheel 52 is supported between theleft and right driving disks 58 and prevented from coming out frombetween them.

More particularly, an outer circumferential face of the driving rollers66 of the driving disk 58 contacts in such a manner as to be pressedagainst an outer circumferential face of the rubber outer peripheralportion 64B of the driven rollers 64 of the main wheel 52. The contactposition between the driving rollers 66 and the driven rollers 64 isleftwardly and rightwardly symmetrical between the left and rightdriving disks 58. Further, the contact position is on that portion ofthe outer circumferential face of the driven roller 64 which ispositioned inwardly (rotational center side) in a diametrical directionwith respect to a diametrical position of the circular ring member 62and the outer circumferential face of the driving roller 66 at thelocation. This signifies that the dimension of the minimum distance inthe direction of the axial line between the driving rollers 66 of theleft and right driving disks 58 is smaller than the outer diametricaldimension of the driven rollers 64.

The driving rollers 66 of the left and right driving disks 58 sandwichthe driven rollers 64 from the opposite left and right sides to supportthe main wheel 52 in a no-axis state between the left and right drivingdisks 58 and can rotate (revolve) around the center of the main wheel 52itself together with the left and right driving disks 58.

An assembly (subassembly) as the traveling unit 50 including the leftand right driving disks 58, left and right driven pulleys 60, hollowaxle 54 and main wheel 52 is configured in such a manner as describedabove.

In this subassembly, the dimension of the distance between the left andright driving disks 58 in the direction of the axial line is uniquelyset to an appropriate value depending upon the distance in the directionof the axial line between the two left and right positioning steppedportions 54A formed on the outer periphery of the hollow axle 54.Consequently, the setting accuracy of friction between the drivingrollers 66 of the driving disk 58 and the driven rollers 64 of the mainwheel 52 is improved, and management of the same is facilitated.

The traveling unit 50 is disposed between the left and right sideportions 12C of the traveling unit supporting section 12 and issupported by the bearing recessed portions 20A of the axle supportingplates 20 at the opposite ends of the hollow axle 54. A reduced diameterend portion 54C is formed at the opposite left and right ends of thehollow axle 54 such that it is reduced in diameter by formation of astepped portion. The left and right reduced diameter end portions 54Care inserted in the bearing recessed portions 20A such that the steppedportions thereof abut with the axle supporting plates 20. A collarmember 69 is fitted on the end portion sides passing through the bearingrecessed portions 20A of the left and right reduced diameter endportions 54C. A headed bolt 72 is inserted in the central through-hole55 of the hollow axle 54 such that it passes a washer 70 from one end.An end portion of the headed bolt 72 projects from the other end side ofthe central through-hole 55, passes through the washer 70 and is screwedwith a nut 74. The head of the headed bolt 72 and the nut 74 press thecollar members 69 through the washers 70. Consequently, each of the axlesupporting plates 20 is sandwiched between the stepped portion of thereduced diameter end portion 54C and the headed bolt 72 or the nut 74with the collar member 69 and the washer 70 interposed therebetween.

Assembly of the traveling unit 50 configured as a subassembly to thetraveling unit supporting section 12 is carried out in the followingmanner. First, the traveling unit 50 is disposed between the left andright side portions 12C of the traveling unit supporting section 12.Then, an outer periphery of the reduced diameter end portions 54C formedat the opposite ends of the hollow axle 54 is fitted from the lower side(opening side) into the downwardly open bearing recessed portion 20A(refer to FIG. 4) of the axle supporting plates 20 fixed to the left andright side portions 12C.

Then, the collar member 69 is fitted with an outer periphery of one ofthe reduced diameter end portions 54C of the hollow axle 54 on the outerside in the direction of the axial line with respect to the portion ofthe reduced diameter end portion 54C at which the reduced diameter endportion 54C engages with the axle supporting plate 20. Then, the headedbolt 72 serving as a supporting shaft is inserted from one of the axialends of the hollow axle 54 into the central through-hole 55 of thehollow axle 54 in a state in which the washer 70 is sandwiched betweenan end face of the collar member 69 and the headed bolt 72. The headedbolt 72 is projected at an end thereof outwardly from the centralthrough-hole 55 through the central through-hole 55.

Then, the other collar member 69 is fitted with an outer periphery ofthe other reduced diameter end portion 54C of the hollow axle 54 on theother side in the direction of the axial line with respect to theportion of the reduced diameter end portion 54C which engages with theaxle supporting plate 20. Then, the nut 74 is tightened to an endthreaded portion 72A of the headed bolt 72 which projects outwardly fromthe central through-hole 55 with the other washer 70 sandwiched betweenthe end face of the collar member 69 and the nut 74. The assembly of thetraveling unit 50 to the traveling unit supporting section 12 iscompleted therewith.

The left and right driving disks 58, left and right driven pulleys 60,hollow axle 54 and main wheel 52 can be unitized without complicatingthe structure in this manner, and the unit can be attached simply to thevehicle body frame 10.

The traveling unit 50 may include a tail wheel unit 80 supported on thehollow axle 54 through a tail wheel arm 78 as in the present embodiment.The tail wheel arm 78 extends substantially linearly at a rear endportion thereof and has a front end portion bifurcated into forkedportions 78A. The tail wheel arm 78 is supported for pivotal motion onthe collar members 69 at the forked portions 78A through ball bearings(radial ball bearing) 76. The collar members 69 are mounted between theforked portions 78A on the left and right reduced diameter end portions54C of the hollow axle 54 so as to dispose the left and right drivingdisks 58, left and right driven pulleys 60 and the main wheel 52 of thetraveling unit 50. Consequently, the tail wheel arm 78 can extend behindthe main wheel 52 without interfering with the left and right drivingdisks 58, left and right driven pulleys 60 and main wheel 52.

A rear side limit stopper 34 is attached to the reinforcement pipe 30.The rear side limit stopper 34 abuts with an upper face of the tailwheel arm 78 to restrict upward pivotal motion of the tail wheel arm 78around the hollow axle 54 (pivotal motion of the tail wheel arm in thecounterclockwise direction in a state in which the vehicle is viewedfrom leftwardly (refer to FIG. 1)). In other words, a maximum rearwardrollover angle (maximum rearward inclination angle) of the vehicle bodyframe 10 is set.

A front side limit stopper 42 is attached to the step supporting pipe36. The front side limit stopper 42 abuts with a lower face of the tailwheel arm 78 to restrict downward pivotal motion of the tail wheel arm78 around the hollow axle 54 (pivotal motion of the tail wheel arm inthe clockwise direction in a state in which the vehicle is viewed fromleftwardly (refer to FIG. 1)). In other words, a forward maximumrollover angle (maximum forward inclination angle) of the vehicle bodyframe 10 is set.

The tail wheel unit 80 is supported at a rear end of the tail wheel arm78. The tail wheel unit 80 includes a tail wheel 82 supported on thetail wheel arm 78, an electric motor 84 for driving the tail wheel 82 torotate, and an outer shell 85 for covering the tail wheel 82 and theelectric motor 84. The tail wheel arm 78 can pivot around the axial lineof the hollow axle 54, and the tail wheel unit 80 places the tail wheel82 into contact with the ground by the weight of the tail wheel unit 80itself.

The tail wheel 82 may be an omnidirectional wheel configured from a ringmember supported for rotation on the tail wheel arm 78 and a free rollerattached for rotation on an outer periphery of the ring member. The ringmember is driven to rotate around the center axial line extending in thevehicle body forward and backward direction in a state in which the freeroller contacts with the ground, namely, around the center axial lineperpendicular to the axial line of the hollow axle 54 (axial line of thecenter of rotation of the main wheel 52) as viewed in plan, by theelectric motor 84.

(Driving Unit)

The left side driving unit 90 is disposed in the upper side cage portion141 as shown in FIGS. 1 and 3. The left side driving unit 90 isconfigured, as shown in FIGS. 6, 7 and 9, an electric motor 92, areduction gear 96 connected to an output power shaft (motor output powershaft) 94 of the electric motor 92, and a driving pulley 100 for a cogbelt disposed leftwardly of the reduction gear 96 and connected to anoutput power shaft (reduction gear output power shaft) 98 of thereduction gear 96.

The reduction gear 96 is of the gear wheel type having two parallel axesand includes a gear box 102 of the wet type having an enclosed structuredirectly connected to the output power shaft side of the electric motor92 as shown in FIG. 10. The reduction gear 96 includes an end portion ofthe motor output power shaft 94, the reduction gear output power shaft98, an intermediate shaft 112, a small gear wheel 114, a large gearwheel 116, another small gear wheel 118, and a large gear wheel 120 inthe gear box 102. The output power shaft 98 is disposed for rotation onthe same axial line with the motor output power shaft 94 by ballbearings 104 and 106. The intermediate shaft 112 is disposed forrotation on an axial line parallel to the reduction gear output powershaft 98 by ball bearings 108 and 110. The small gear wheel 114 is fixedto an end portion of the motor output power shaft 94. The large gearwheel 116 is fixed to the intermediate shaft 112 and meshes with thesmall gear wheel 114. The small gear wheel 118 is fixed to theintermediate shaft 112, and the large gear wheel 120 is fixed to thereduction gear output power shaft 98 and meshes with the small gearwheel 118.

In the reduction gear 96, a disposition portion of the intermediateshaft 112 thereof projects outwardly in a radial direction from theouter face of the electric motor 92, and this projecting portion 102A ispositioned on the obliquely upper rear side with respect to the positionof the center axial line of the electric motor 92.

An end portion of the reduction gear output power shaft 98 projects tothe opposite side (left side) of the gear box 102 to the side of theelectric motor 92, and the driving pulley 100 is fixed to the endportion. In other words, the reduction gear 96 is disposed between theelectric motor 92 and the reduction gear output power shaft 98.

A plurality of threaded holes (not shown) are formed in a left wall ofthe gear box 102, and a plurality of (in the example shown, three) boltpenetrating holes 22A are formed in the left side driving unitattachment plate 22 as shown in FIG. 4. Attachment bolts 26 extendingthrough the bolt penetrating holes 22A are screwed in the threaded holesto fix the reduction gear 96, namely, the left side driving unit 90, tothe left side driving unit attachment plate 22. It is to be noted thatthe left side driving unit 90 can be placed into the upper side cageportion 141 from the right side, at which the left side driving unitattachment plate 22 does not exist and which is open, beginning with thereduction gear 96.

The reduction gear output power shaft 98 projects outwardly through acutaway portion 22B (refer to FIG. 4) formed in the left side drivingunit attachment plate 22, and the driving pulley 100 is attached to aposition of the outwardly projecting end of the reduction gear outputpower shaft 98 very proximate to the outer side face of the left sidedriving unit attachment plate 22. A cog belt 122 extends between thedriving pulley 100 and the driven pulleys 60. Since the driving pulley100 around which the cog belt 122 extends is positioned on the left sidedriving unit attachment plate 22 side together with the reduction gearoutput power shaft 98, the left side power transmission sectionincluding the driving pulley 100 is supported more firmly by the leftside driving unit attachment plate 22. The left side driving unitattachment plate 22 is an attachment plate of the left side driving unit90 to the vehicle body frame 10 and simultaneously serves as a gussetwhich acts to raise the rigidity of the upper side cage portion 141 andraise the supporting rigidity of the left side power transmissionsection.

It is to be noted that, since the cutaway portion 22B of the left sidedriving unit attachment plate 22 is so sized that the driving pulley 100in a state in which it is fixed to the reduction gear output power shaft98 can pass therethrough in the vehicle widthwise direction, the leftside driving unit 90 wherein the driving pulley 100 is fixed to thereduction gear output power shaft 98 can be assembled to the upper sidecage portion 141.

Each of the bolt penetrating holes 22A is an elongated hole elongated inthe upward and downward direction, and the fixing position of the leftside driving unit 90 to the left side driving unit attachment plate 22in the upward and downward direction can be changed within the range ofthe elongated hole. By changing the fixing position of the left sidedriving unit 90 in the upward and downward direction, the tension to beapplied to the cog belt 122 can be changed. In short, the boltpenetrating hole 22A cooperates with the mounting bolt 26, which extendsthrough the bolt penetrating hole 22A, so as to serve as a guide portionfor the movement of the left side driving unit 90 in the upward anddownward direction, and the tension to be applied to the cog belt 122 ischanged by change of the fixing position of the left side driving unit90 in the upward and downward direction.

An adjustment bolt 124 is attached to the sixth pipe 14F such that itextends upwardly and downwardly through the sixth pipe 14F as shown inFIGS. 4 and 9. The adjustment bolt 124 is screwed in a threaded hole(not shown) formed in an upper wall of the gear box 102.

By changing the screwed amount of the adjustment bolt 124 into thethreaded hole in a state in which the mounting bolts 26 are loosened,the entire left side driving unit 90 moves upwardly or downwardly withrespect to the upper side cage portion 141 (sixth pipe 14F). By theupward or downward movement of the left side driving unit 90, thetension to be applied to the cog belt 122 can be adjusted. By fasteningthe adjustment bolt 124 to the sixth pipe 14F by a lock nut 126, thetension variation of the cog belt 122 can be suppressed.

The right side driving unit 130 is disposed in the lower side cageportion 14J as shown in FIGS. 1 and 3. The right side driving unit 130is equivalent to the left side driving unit 90 reversed leftwardly andrightwardly. As shown in FIGS. 6, 7 and 9, the right side driving unit130 is configured from an electric motor 132, a reduction gear 136attached to the output power shaft (not shown) side (right side) of theelectric motor 132, and a driving pulley 140 for a cog belt attached toan output power shaft (reduction gear output power shaft) 138hereinafter described of the reduction gear 136.

The reduction gear 136 is of the gear wheel type of two parallel shaftsand includes a wet type gear box 142 of an enclosed structure directlycoupled to the output power shaft side of the electric motor 132. Thegear box 142 has an internal structure similar to that of the reductiongear 96 including the reduction ratio except that it has a leftwardlyand rightwardly inversed disposition, and therefore, detaileddescription of the internal structure thereof is omitted herein. Thereduction gear 136 projects, at a disposition portion of an intermediateshaft (not shown) thereof, outwardly in a radial direction from an outerprofile of the electric motor 132. This projecting portion 142A ispositioned on the front side of the vehicle body with respect to theposition of the axial line of the center of the electric motor 132.

The reduction gear output power shaft 138 projects, at an end portionthereof, to the opposite side (right side) of the gear box 142 to theside of the electric motor 132, and the driving pulley 140 is fixed tothe end portion thereof. In other words, the reduction gear 136 isdisposed between the electric motor 132 and the reduction gear outputpower shaft 138.

A plurality of threaded holes (not shown) are formed in the right wallof the gear box 142, and a plurality of (in the example shown, three)bolt penetrating holes 24A are formed in the right side driving unitattachment plate 24. By screwing mounting bolts 28 penetrating the boltpenetrating holes 24A into the threaded holes, the reduction gear 136,namely, the right side driving unit 130, is fixed to the right sidedriving unit attachment plate 24. It is to be noted that the right sidedriving unit 130 can be placed into the lower side cage portion 14J fromthe left side, on which the right side driving unit attachment plate 24does not exist and which is open, beginning with the reduction gear 136.

The reduction gear output power shaft 138 passes through a cutawayportion 24B (refer to FIG. 4) formed in the right side driving unitattachment plate 24 and projects to the outer side, and the drivingpulley 140 is attached to a position of the outer side projecting end ofthe reduction gear output power shaft 138 very close to the outer sideface of the right side driving unit attachment plate 24. An endless cogbelt 144 extends between and around the driving pulley 140 and the rightside driven pulley 60. The driving pulley 140 around which the cog belt144 extends is positioned on the side of the right side driving unitattachment plate 24 together with the reduction gear output power shaft138. Therefore, the right side power transmission section including thedriving pulley 140 is supported firmly by the right side driving unitattachment plate 24. The right side driving unit attachment plate 24servers as an attachment plate for the right side driving unit 130 tothe vehicle body frame 10 and simultaneously acts as a gusset to raisethe rigidity of the lower side cage portion 14J and raise the supportingrigidity of the right side power transmission section.

Each bolt penetrating hole 24A is an elongated hole elongated in theupward and downward direction, and the fixing position of the right sidedriving unit 130 to the right side driving unit attachment plate 24 inthe upward and downward direction can be changed within the range ofthis elongated hole. This serves as adjustment mechanism for the initialtension. By changing the fixing position of the right side driving unit130 in the upward and downward direction, the tension to be applied tothe cog belt 144 can be changed. In other words, the bolt penetratinghole 24A cooperates with the mounting bolt 28 extending through the boltpenetrating hole 24A to serve as a guide portion for movement of theright side driving unit 130 in the upward and downward direction.Further, the tension to be applied to the cog belt 144 is changed bychanging the fixing position of the right side driving unit 130 in theupward and downward direction.

An adjustment bolt 146 is attached to the seventh pipe 14G such that itextends upwardly and downwardly through the seventh pipe 14G as shown inFIGS. 4 and 9. The adjustment bolt 146 is screwed in a threaded hole(not shown) formed in an upper wall of the gear box 142.

By changing the screwed amount of the adjustment bolt 146 into thethreaded hole in a state in which the mounting bolts 28 are loosened,the right side driving unit 130 moves upwardly or downwardly withrespect to the lower side cage portion 14J (seventh pipe 14G). Thetension to be applied to the cog belt 144 can be adjusted by this upwardor downward movement of the right side driving unit 130. By fasteningthe adjustment bolt 146 to the seventh pipe 14G by a lock nut 148, thetension variation of the cog belt 144 can be suppressed.

The adjustment bolts 124 and 146 hang the left side driving unit 90 andthe right side driving unit 130 from above and support the left sidedriving unit 90 and the right side driving unit 130 at positions atwhich they are opposed to the cog belts 122 and 144 in a direction inwhich the tension is generated. Therefore, positioning of the left sidedriving unit 90 and the right side driving unit 130 upon tensionadjustment is facilitated.

It is to be noted that such setting is used that, even if the left sidedriving unit 90 on the upper stage is positioned at its lowermostposition, a space 149 into which a tool T or a jig for turning theadjustment bolt 146 can be inserted is assured between a bottom portionof the left side driving unit 90 and the head of the adjustment bolt 146on the lower stage. Where the lower frame (fourth pipe 14D, fifth pipe14E) of the upper side cage portion 141 serves as an upper frame of thelower side cage portion 14J and the adjustment bolt 146 is attached tothe seventh pipe 14G which bridges the fourth pipe 14D and the fifthpipe 14E as in the case of the embodiment shown in the figures, the headof the adjustment bolt 146 is accessed from the side (right side) towhich the left side driving unit attachment plate 22 is not attached.Consequently, the tension to the cog belt 144 can be adjusted by anoperation of the adjustment bolt 146 without being obstructed by the cogbelt 122. It is to be noted that, by accessing also the adjustment bolt124 on the upper stage from the side (right side) to which the left sidedriving unit attachment plate 22 is not attached, tension adjustment ofthe cog belts 122 and 144 can be carried out from the same side.

The left and right driven pulleys 60 have an equal number of teeth, andthe left and right driving pulleys 100 and 140 have an equal number ofteeth smaller than the number of teeth of the left and right drivenpulleys 60. By the difference in number of teeth between the drivenpulleys 60 and the driving pulleys 100 and 140, secondary speedreduction by an equal reduction ratio between the left and the right iscarried out. Although the left and right cog belts 122 and 144 aredifferent in length from each other, since the reduction ratio betweenthe driven pulleys 60 and the driving pulleys 100 and 140 depends uponthe ratio of numbers of teeth independently of the belt length, thedriven pulleys 60 and the driving pulleys 100 and 140 can be made commonbetween the left and the right.

In this manner, the left side driving unit 90 and the right side drivingunit 130 are disposed in an offset state on the two upper and lowerstages while they are reversed leftwardly and rightwardly relative toeach other, and overlap in most part thereof with each other as viewedin plan. The electric motor 92 of the left side driving unit 90 on theupper stage is provided in a displaced relationship to the right sideopposite to the disposition side of the reduction gear 96 with respectto a vehicle body center line C (refer to FIG. 6) in the vehiclewidthwise direction (leftward and rightward direction). Meanwhile, theelectric motor 132 of the right side driving unit 130 on the lower stageis provided in a displaced relationship to the left side opposite to thearrangement side of the reduction gear 136 with respect to the vehiclebody center line C (refer to FIG. 6) in the vehicle widthwise direction(leftward and rightward direction).

By this disposition, the electric motor 92 of the left side driving unit90 on the upper stage is positioned just above the reduction gear 136 ofthe right side driving unit 130 on the lower stage. Further, thereduction gear 96 of the left side driving unit 90 on the upper stage ispositioned just above the electric motor 132 of the right side drivingunit 130 on the lower stage.

In the inverted pendulum type vehicle 1 of the present embodiment, theleft side driving unit 90 and the right side driving unit 130 aredisposed in an offset state on the two upper and second stages atpositions above the main wheel 52 and overlap at most part thereof witheach other as viewed in plan as described hereinabove. Therefore, incomparison with a case in which the electric motors 92 and 132 aredisposed in a juxtaposed relationship in the vehicle widthwise directionat the same height on the vehicle, a greater disposition space in thevehicle widthwise direction can be taken for each of the left sidedriving unit 90 and the right side driving unit 130 in the same vehiclebody width.

Consequently, upsizing (increase in torque) of the electric motors 92and 132 and addition of the reduction gears 96 and 136 become possiblewithout increasing the vehicle body width. As the reduction gears 96 and136 are installed, driving torque of the driving disk 58 and hencedriving torque of the main wheel 52 can be increased. Besides, since thereduction gears 96 and 136 are of the two parallel shaft type in whichthe output power shafts (94) of the electric motors 92 and 132 and theoutput power shafts 98 and 138 of the reduction gears 96 and 136 aredisposed on the same axial line, unitization of the electric motors 92and 132 in a small mass can be anticipated with a compact structure.Further, the left side driving unit 90 and the right side driving unit130 having output power torque ready for a model of different drivingtorque can be disposed suitably without changing the vehicleclassification.

Further, since the left side driving unit 90 and the right side drivingunit 130 are disposed on the two upper and lower stages, the position ofthe center of gravity of the inverted pendulum type vehicle 1 can bepositioned upwardly and the inverted pendulum control of the invertedpendulum type vehicle 1 is facilitated.

Since the left side driving unit 90 and the right side driving unit 130are disposed in a leftward and rightwardly reversed state on the twoupper and lower stages, the balance in weight between the left and theright is enhanced. Besides, the electric motors 92 and 132, which make aheat source, are disposed in a spaced relationship from each other inthe vehicle widthwise direction, and heat damage by neighboringdisposition of the heat sources can be avoided. Further, since theelectric motors 92 and 132 are positioned on the opened side on whichthe left side driving unit attachment plate 22 and the right sidedriving unit attachment plate 24 do not exist, also the coolingperformance is enhanced advantageously and wiring and connection of aharness for electric power (not shown) to the electric motors 92 and 132are facilitated.

While the projecting portion 102A of the reduction gear 96 of the leftside driving unit 90 is positioned on the obliquely upward rearward sidewith respect to the position of the center axial line of the electricmotor 92, the projecting portion 142A of the reduction gear 136 of theright side driving unit 130 is positioned forwardly with respect to theposition of the center axial line of the electric motor 132. In otherwords, the projecting directions of the projecting portions 102A and142A of the reduction gears 96 and 136 are different between the upperstage and the lower stage. Therefore, effective utilization of the spaceand adjustment in weight balance of the vehicle body in the forward andbackward direction can be anticipated.

Where the projecting portion 102A of the reduction gear 96 on the upperstage is positioned on the obliquely upward rearward side with respectto the position of the center axial line of the electric motor 92, theposition of the center of gravity of the inverted pendulum type vehicle1 is positioned further upwardly, and inverted pendulum control of theinverted pendulum type vehicle 1 is facilitated. That the projectingportion 142A of the reduction gear 136 of the right side driving unit130 is positioned forwardly with respect to the position of the centeraxial line of the electric motor 132 coincides with that the center ofrotation of the reduction gear output power shaft 138 of the right sidedriving unit 130 is positioned in a displaced relationship to thevehicle body rear side from the center of rotation of the reduction gearoutput power shaft 98 of the left side driving unit 90. This contributesto space-saving by effective utilization of the space.

Since the left side driving unit 90 and the right side driving unit 130are assemblies of the electric motors 92 and 132 and the reduction gears96 and 136, respectively, the gear boxes 102 and 142 of the reductiongears 96 and 136 which are moist chambers by lubricating oil can beaggregated on the side of the left side driving unit 90 and the rightside driving unit 130 separately from the cog belt systems of the drytype (driving pulleys 100 and 140, cog belts 122 and 144 and left andright driven pulleys 60). Consequently, the maintenance performance ofthe left side driving unit 90, right side driving unit 130 and thedriving systems by the cog belt systems is enhanced.

Further, assembly of the running and driving systems can be carried outreadily only by the following procedure. In particular, the subassemblyof the left and right driving disks 58 and the left and right drivenpulleys 60 assembled to the hollow axle 54 and the main wheel 52assembled between the left and right driving disks 58, namely, thetraveling unit, is attached to the axle supporting plates 20 by the bolt72 and the nut 74. Then, the left side driving unit 90 and the rightside driving unit 130 to which the driving pulleys 100 and 140 areassembled, respectively, are attached to the driving unit supportingsection 14. Further, the cog belts 122 and 144 are wrapped around thedriving pulleys 100 and 140 and the left and right driven pulleys 60.

As shown in FIG. 9, the center of rotation of the reduction gear outputpower shaft 98 of the left side driving unit 90 is located on a verticalline P which passes the center of the hollow axle 54. However, thecenter of rotation of the reduction gear output power shaft 138 of theright side driving unit 130 is positioned in a displaced relationship tothe vehicle body rear side with respect to the center of rotation of thevertical line P which passes the center of the hollow axle 54 as viewedin a side elevation.

(Seat Unit)

As shown in FIG. 5, a cylindrical bush 47 made of resin is fitted in anupper half portion of the inside of the center post 44. The cylindricalbush 47 has an annular flange portion 47A extending outwardly indiametrical directions at an upper end thereof. The cylindrical bush 47is sandwiched at the flange portion 47A thereof between an upper endface of the center post 44 and a retaining member 49 fixed to the centerpost 44 such that the cylindrical bush 47 is supported on the centerpost 44 against movement in the direction of the axial line.

A telescopic strut 180 is inserted in the center post 44 and serves as asupport post for supporting the seat for upward and downward movement.In particular, the telescopic strut 180 is disposed between the drivingunits 90 and 130 and the battery pack 250 in the vehicle body forwardand backward direction. Consequently, when the telescopic strut 180 isused to adjust the height of the seat, the space of the vehicle body isutilized effectively to avoid upsizing of the vehicle body while thedriving units 90 and 130 and the battery pack 250 which arecomparatively heavy can be disposed in a good balance forwardly andbackwardly of the telescopic strut 180 (seat 200) thereby to maintain agood gravity center balance of the vehicle body. The telescopic strut180 is configured from a gas spring with a lock (lifting apparatus ofthe cylinder type) and is inserted in the center post 44 with a pistonrod 182 positioned on the lower side while an end portion of the pistonrod 182 is fixed to a bottom portion of the center post 44 by a nut 45.A cylinder tube 184 of the telescopic strut 180 is fitted for slidingmovement with the cylindrical bush 47 such that it can move upwardly anddownwardly with respect to the vehicle body frame 10.

An upper end of the cylinder tube 184 projects upwardly from the centerpost 44. The cylinder tube 184 is fixed at the upper end thereof to aseat frame 202 of the seat (saddle) 200. The seat 200 is configured fromthe above-described seat frame 202 formed in a substantiallyquadrangular frame shape by bending a pipe member. The seat 200 isconfigured further from a base member 201 in the form of a plate fixedto the seat frame 202, and a seat main body 206 attached to an upperportion of the base member 201 and having a cushioning property. Theseat 200 is configured further from a seat bottom cover 204 attached toa lower portion of the base member 201, and side guard members 207attached to the opposite left and right sides of the seat bottom cover204. A seat lifting lever (operation lever) 198 (refer to FIG. 11) forcarrying out unlocking of the telescopic strut 180 is disposed on oneside portion of the seat bottom cover 204.

The side guard members 207 are made of a comparatively hard material(here, rubber) and are provided so as to be positioned on the most outersides in the widthwise direction (leftward and rightward direction) ofthe seat 200. Consequently, even if the seat main body 206 is made of acomparatively soft material (here, polyurethane) taking the ridingcomfort and so forth into consideration, the occupant can assume astabilized riding posture by grasping the left and right side guardmembers 207 as occasion demands when the occupant gets on the invertedpendulum type vehicle 1. Further, as shown in FIG. 2, the components ofthe vehicle body are provided so as to be positioned on the inner sideof an imaginary line L1 which connects outer edges of the left and rightside guard members 207 and outer edges of the left and right steps 40 toeach other. In other words, the seat 200 and the steps 40 are providedwith a width greater than that of the outer shell 18 in the leftward andrightward direction. Consequently, also in a state in which the vehiclebody rolls over to the left or right, only one of the side guard members207 and one of the steps 40 contact with the floor face or the like, andtherefore, occurrence of damage or the like to the components of thevehicle body can be prevented.

In the seat supporting structure described above, the seat 200 isattached to the telescopic strut 180 such that it is positioned at anuppermost portion of the vehicle body. The driving units 90 and 130 andpart of the battery unit are disposed on the lower side of the seat 200as shown also in FIG. 1. Consequently, the vehicle body can becompactified while it can be maintained in a good gravity centerbalance. If the seat lifting lever 198 of the telescopic strut 180 isoperated, then the locking of the telescopic strut 180 is canceled andthe cylinder tube 184 is moved upwardly by an internal gas pressure ofthe telescopic strut 180. Consequently, the height of the seat main body206 can be adjusted freely in accordance with the physique, preferenceand so forth of the occupant.

(Seat Lifting Mechanism)

Now, details of a lifting mechanism for the seat 200 which uses thetelescopic strut 180 are described with reference to FIGS. 11 to 15. Asshown in FIGS. 11 and 12, the seat frame 202 includes an annular mainframe 211 fastened to a lower face of the base member 201 by a pluralityof bolts and open in the upward and downward directions, and a pair ofsub frames 212 extending substantially in parallel to each other in sucha manner as to cross the main frame 211 in the vehicle body forward andbackward direction. The main frame 211 is connected at a rear portionthereof to a first connection base portion 213 (refer to FIG. 5) whichis positioned on a rear side circumferential face of the cylinder tube184 of the telescopic strut 180.

The rear ends of the sub frames 212 are curved to the inner side andconnected to each other to form a U-shaped connection portion 214. Thisconnection portion 214 is connected to a second connection base portion215 (refer to FIG. 5) which is positioned on a front sidecircumferential face of the cylinder tube 184. The second connectionbase portion 215 is positioned downwardly with respect to the connectionbase portion 213 to which the main frame 211 is connected. Further, thesub frames 212 are connected at a front end thereof to the innerperipheral face of a front portion of the main frame 211.

As shown in FIG. 13, the seat lifting lever 198 includes a lever arm(first arm) 222 having a crank shape and an operation arm (second arm)212 for engaging with the lever arm 221. On the lever arm 221, a leverportion 221 b on the left end side is rocked in response to an operationinput to a straight portion 221 a on the right end side which has anoperating piece (operation portion) 220 provided at a terminal endthereof. The operation arm 222 pivots in response to a rocking motion ofthe lever portion 221 b to depress an unlocking button (lift adjustmentbutton) 181 of the telescopic strut 180.

The straight portion 221 a of the lever arm 221 extends in the leftwardand rightward direction and is attached for pivotal motion to anattachment plate 223 by a mounting bracket 224 having a U-shapedsupporting portion. The attachment plate 223 extends between the mainframe 211 and one of the sub frames 212 below the seat frame 202 asshown in FIG. 11. The lever portion 221 b is curved rearwardly from aleft end of the straight portion 221 a, and an end of the lever portion221 b further extends in the leftward and rightward direction andengaged with a front side upper portion of the operation arm 222.

As shown in FIG. 13, the operation arm 222 includes a main body portion230 in the form of a flat plate in which an opening 230 a through whichan upper portion of the cylinder tube 184 extends is formed, and aperipheral wall portion 231 provided projecting upwardly on left andright edges and a front edge of the main body portion 230. Theperipheral wall portion 231 is cut away at a right front portion thereofsuch that the lever portion 221 b can abut with an upper face of themain body portion 230. The lever portion 221 b is locked by the frontside of the peripheral wall portion 231 such that coming off thereoffrom the upper face of the main body portion 230 is prevented.

A pivot shaft 232 extends in the leftward and rightward direction and isfitted in left and right rear portions of the peripheral wall portion231. The pivot shaft 232 is supported by a pair of supporting pieces 233provided in an upwardly projecting manner from a rear portion of themain frame 211. The pivot shaft 232 is positioned on the vehicle bodyrear side with respect to the telescopic strut 180, and an engagingportion 222 a of the operation arm 222 with the lever portion 221 b(front side upper portion of the main body portion 230) is positioned onthe vehicle body front side with respect to the telescopic strut 180(refer to FIG. 5). By such a configuration as just described, a higherlever ratio (ratio between the distance from the pivot shaft 232 to theengaging portion 222 a with the lever portion 221 b and the distancefrom the pivot shaft 232 to the abutting portion with the unlockingbutton 181) can be assured in the limited space below the seat main body206, and the occupant can depress the unlocking button 181 with lowerforce. Further, the operation arm 222 is disposed in a space between thesub frames 212 in pair and pivotally moves in the space. In other words,with the seat frame 202, it is possible to assure the strength of thedisposition space of the seat lifting lever 198 below the seat 200 andeliminate an influence of disturbance to a lever operation which canpossibly occur upon movement of a moving body.

A pushdown rod 234 is provided on the operation arm 222 such that itcrosses the opening 230 a of the main body portion 230 in the leftwardand rightward direction above the opening 230 a. A lower face of thepushdown rod 234 is in a normally contacting state with the unlockingbutton 181 which is biased upwardly. A pair of leg portions 234 a areformed at the opposite ends of the pushdown rod 234 such that theyextend substantially in the vertical direction. The leg portions 234 aare fixed to left and right circumferential faces of the peripheral wallportion 231.

When the height of the seat 200 is to be adjusted, the lever arm 221 canbe pivoted by the occupant lifting up the front end of the operatingpiece 220 (refer to an arrow mark A in FIG. 13). At this time, the leverportion 221 b of the lever arm 221 is rocked downwardly to press thefront side of the operation arm 222 downwardly thereby to pivot theoperation arm 222 downwardly. As a result, the unlocking button 181 isdepressed by the pushdown rod 234 moved downwardly and the cylinder tube184 of the telescopic strut 180 whose locking is cancelled movesupwardly as shown in FIG. 14. The occupant can cancel the depression ofthe unlocking button 181 to place the telescopic strut 180 into a lockedstate again by canceling the operation of the operating piece 220 whenthe seat 200 moves upwardly to a desired height. It is to be noted that,when the position of the seat 200 is to be moved downwardly, theoccupant may depress the upper face of the seat 200 downwardly in thestate in which the front end of the operating piece 220 is liftedupwardly and cancel the operation of the operating piece 220 at adesired height. Further, pivotal motion of the lever arm 221 in theopposite direction (direction in which the operation arm 222 is notpressed) is restricted by a pivotal motion restricting pin 235 whichabuts with the lever portion 221 b.

The seat lifting lever 198 is accommodated in the seat 200 except theoperating piece 220 and a portion thereof on the right end side of thelever arm 221 to which the operating piece 220 is attached. When theseat lifting lever 198 is to be incorporated into the seat 200, thecomponents except the operating piece 220 are assembled into the seat asshown in FIG. 15, and the seat 200 is assembled in a state in which theright end of the lever arm 221 extends from an opening (slit) 236 formedin the seat bottom cover 204. Then, in a state in which the entire seat200 is assembled finally, the operating piece 220 can be fitted into theright end of the lever arm 221 and fixed by a hexagon cap nut 237.Consequently, the assembling performance is good.

The seat lifting lever 198 is provided in such a manner as to overlapwith the lower side of the seat 200 as viewed in plan including part ofthe operating piece 220 and the lever arm 221 which project from theopening 236. Further, at least the operating piece 220 positioned on theoutermost side from the seat lifting lever 198 is provided such that itis positioned on the outer side with respect to the outer shell 18 belowthe seat 200. Consequently, in the compact configuration wherein theoccupant gets on the vehicle body (outer shell) in a posture in which itsandwiches the vehicle body with both legs, while the seat lifting lever198 of the telescopic strut 180 can be accessed readily, unintendedcontact with the seat lifting lever 198 can be prevented.

(Supporting Structure for the Battery Pack)

As shown in FIGS. 1 and 3, a battery case 251 for supporting the batterypack 250 is supported on the shelf board 17. The battery case 251includes a bottom plate 253 of a rectangular shape, a front side wall254 and a pair of left and right side walls 255 erected uprightly on thefront side and the opposite left and right sides of the bottom plate253. The paired left and right side walls 255 extend upwardly fartherthan the front side wall 254, and the battery case 251 is formed in abox shape having an opening 257 (refer to FIG. 16) which continues froman upper portion of the front side to an overall region of an upperportion and a rear portion. It is to be noted that, in anotherembodiment, preferably the opening 257 is open at least upwardly, andthe rear portion side face may be closed. The left and right side walls255 are depressed to the front side at a rear edge of an intermediateportion thereof in the upward and downward direction to expand theopening 257. Consequently, the battery pack 250 supported by the batterycase 251 is exposed at an intermediate portion of the side face rearportion side in the upward and downward direction.

A bracket 258 is coupled to the center post 44 such that it extendsrearwardly, and the front side wall 254 of the battery case 251 iscoupled at a front face thereof to the bracket 258. The outer shell 18is disposed along an edge portion of the opening 257 such that theopening 257 of the battery case 251 is exposed to the outside.

The battery pack 250 is formed substantially in a vertically elongatedparallelepiped. A locking protrusion 262 is provided in a projectingmanner on an upper face of the bottom plate 253 of the battery case 251,and an accepting hole 263 is provided in a concave state on the bottomface of the battery pack 250 such that the locking protrusion 262 can beaccepted in the accepting hole 263. The locking protrusion 262 projectsinto the accepting hole 263 to restrict sliding movement of the batterypack 250 in a direction along the face with respect to the bottom plate253 while the battery pack 250 can be tilted rearwardly around thelocking protrusion 262. In particular, by engagement between theaccepting hole 263 and the locking protrusion 262, the battery pack 250can pivot between a mounted position at which the front face thereofextends along the front side wall 254 and a removable position at whichthe front face thereof is inclined rearwardly with respect to the frontside wall 254. At the mounted position, terminals (not shown) formed onthe battery pack 250 and the battery case 251 contact with each other toallow power feeding from the battery pack 250. It is to be noted that,in other embodiments, the locking protrusion 262 may not be formed onthe bottom plate 253 but may be formed on the front side wall 254.

As shown in FIGS. 1 and 16, a lid 260 is supported for pivotal motion atan upper edge portion of the front side wall 254 and forms an upper wallof the battery case 251. The lid 260 includes a front plate 265 forclosing up an opening formed at an upper portion of the front side wall254, an upper plate 266 connected to an upper edge of the front plate265 with an angle and configured to close up an opening formed betweenupper ends of the left and right side walls 255, and a rear plate 267connected to a rear edge of the upper plate 266 with an angle. The lid260 has a substantially channel-shaped cross section.

The lid 260 has a pair of left and right arms 268 provided in aprojecting manner on a reverse face (rear face) of the front plate 265.A shaft 269 is supported at an upper portion of a rear face of the frontside wall 254 such that it extends in the leftward and rightwarddirection. The lid 260 is supported at the arms 268 thereof for pivotalmotion by the shaft 269 such that it is supported on an upper edgeportion of the front side wall 254 for pivotal motion around the axialline extending in the leftward and rightward direction. The lid 260 canpivot between a closing position at which it closes an upper portion ofthe battery case 251 and an opening position to which the lid 260 ispivoted in the counterclockwise direction as viewed from the right sideto the front side. A torsion coil spring (not shown) is interposedbetween the lid 260 and the front side wall 254 and supported by theshaft 269. Consequently, the lid 260 is biased to the opening positionby the torsion coil spring. It is to be noted that the lid 260 can pivotonly in a state in which the telescopic strut 180 stretches until theseat 200 is disposed at the upper position at which it does notinterfere with the lid 260. When the telescopic strut 180 is contracteduntil the seat 200 is positioned at the lower position (seatingposition), the seat 200 abuts at a rear end face thereof with the frontplate 265 of the lid 260 to restrict pivotal motion of the lid 260 fromthe closing position to the opening position. The lid 260 cooperates, atthe closing position, with the outer shell 18 to smoothly form an outerface of the inverted pendulum type vehicle 1.

On an upper face of the battery pack 250, one latch hole 270 and a pairof left and right accepting holes 271 are formed such that the acceptingholes 271 are disposed on the left and right of the latch hole 270.Meanwhile, on a reverse face of the upper plate 266 of the lid 260, onelatch 273 and a pair of left and right projections 274 are provided in aprojecting manner such that the projections 274 are disposed on the leftand right of the latch 273. By disposing the battery pack 250 at themounted position and disposing the lid 260 at the closing position, thepaired left and right projections 274 plunge into the paired left andright accepting holes 271, and the latch 273 plunges into the latch hole270. The latch 273 and the latch hole 270 are formed in a knownpush-push mechanism such that, if the latch 273 is pushed once into thelatch hole 270, then the latch 273 is locked by the latch hole 270, andthen if the latch 273 is pushed into the latch hole 270 again in thestate in which the latch 273 is locked by the latch hole 270, thelocking of the latch 273 by the latch hole 270 is canceled. As the latch273 is engaged with the latch hole 270 and the projections 274 areengaged with the accepting holes 271, the lid 260 is held at the closedposition and the battery pack 250 is held at the mounted position.

When the battery pack 250 is to be mounted on the battery case 251, thetelescopic strut 180 is stretched first to dispose the seat 200 to theupper position. Consequently, since the lid 260 is permitted to pivot tothe opening position, the lid 260 is disposed to the opening position.Then, the battery pack 250 is tilted to approach from the rear of thebattery case 251 so that the lower end portion thereof comes to thefront side, whereupon the locking protrusion 262 of the battery case 251is projected into the receiving hole of the battery pack 250 to disposethe battery pack 250 to the removable position. Then, the battery pack250 is pivoted around the locking protrusion 262 with respect to thebattery case 251 to dispose the battery pack 250 to the mountedposition. Then, the lid 260 is pivoted to the closing position to placethe latch 273 and the latch hole 270 and place the projections 274 andthe accepting holes 271 into engagement with each other. Consequently,the battery pack 250 is mounted on the battery case 251. Then, thetelescopic strut 180 is contracted to dispose the seat 200 at the lowerposition thereby to restrict pivotal motion of the lid 260.Consequently, the lid 260 is pushed in downwardly, and since the lid 260cannot pivot even if the engagement between the latch 273 and the latchhole 270 is canceled, the battery pack 250 is maintained in the state inwhich it is supported between the battery case 251 and the lid 260. Whenthe battery pack 250 is to be removed from the battery case 251, thetelescopic strut 180 is stretched to dispose the seat 200 to the upperposition to permit pivotal motion of the lid 260 to the open position.

(Electrical Unit)

As shown in FIG. 1, the electrical unit 300 includes a main wheelcontrolling power drive unit 301 (hereinafter referred to as main wheelPDU) for controlling the left and right driving units 90 and 130, and atail wheel controlling power drive unit 302 (hereinafter referred to astail wheel PDU) for controlling the tail wheel unit 80. The electricalunit 300 further includes a DC-DC converter 304 (hereinafter referred toas converter) for stepping down a dc voltage supplied from the batterypack to a predetermined dc voltage, and an I/O interface unit 305(hereinafter referred to as I/O unit) for transferring a signal to andfrom various sensors. The electrical unit 300 further includes a switchunit 306 for operating on/off of a power supply, and a gyro sensor 308for detecting an inclination angle and an angular speed of the vehiclebody frame 10 (inverted pendulum type vehicle 1) with respect to apredetermined axial line (for example, a vertical line). To the I/O unit305, signals from a seating sensor 307 incorporated in the seat unit170, the gyro sensor 308 and the switch unit 306 are inputted.

As shown in FIG. 1, in the vehicle body frame 10, the front edge portion12A of the traveling unit supporting section 12 is disposed mostforwardly as viewed in side elevation. Since the front end of thedriving unit supporting section 14 is formed from the first pipe 14A andthe second pipe 14B which are inclined rearwardly toward the upper sidefrom the front edge portion 12A, it is displaced rearwardly from thefront edge portion 12A. The front end, on the outer periphery of themain wheel 52, of the traveling unit 50 disposed below the travelingunit supporting section 12 projects forwardly farther than the frontedge portion 12A. In order to include the vehicle body frame 10 and thetraveling unit 50, the front face portion of the outer shell 18 isformed in a curved face which extends smoothly from the front side upperend of the driving unit supporting section 14 to the outer peripheralfront end of the main wheel 52. Consequently, on the front side of thevehicle body frame 10, a space 315 is formed between the front side ofthe vehicle body frame 10 and the front face portion of the outer shell18. Particularly, the space 315 is formed such that it extends from thefront side of the first pipe 14A and the second pipe 14B of the drivingunit supporting section 14 to the front side of the traveling unitsupporting section 12. The electrical unit 300 is disposed in the space315.

The main wheel PDU 301 and the tail wheel PDU 302 include amicrocomputer configured from a CPU, a memory and so forth, and aswitching circuit for controlling current or voltage to be supplied tothe electric motors 84, 92 and 132. To the main wheel PDU 301 and thetail wheel PDU 302, signals from the seating sensor 307, gyro sensor 308and switch unit 306 are inputted through the I/O unit 305. The mainwheel PDU 301 controls the electric motors 92 and 132 in response tosignals from the seating sensor 307 and the gyro sensor 308 based oninverted pendulum control set in advance. The tail wheel PDU 302controls the electric motor 84 in response to signals from the seatingsensor 307 and the gyro sensor 308 based on a turning control rule setin advance.

As shown in FIGS. 1 and 3, the main wheel PDU 301 and the tail wheel PDU302 are supported on the same face of a first board 320 of a rectangularshape. The main wheel PDU 301 is supported on one side of the firstboard 320 in the longitudinal direction while the tail wheel PDU 302 issupported on the other side. Further, a fan 321 is provided at the endportion of the first board 320 at which the main wheel PDU 301 isdisposed. In the present embodiment, the fan 321 is a known axial flowfan having a frame body of a rectangular shape and rotary wingssupported for rotation in the frame body. The fan 321 is disposed on thefirst board 320 such that the axial line of rotation thereof extends inparallel to the longitudinal direction of the first board 320. The mainwheel PDU 301 is greater than the tail wheel PDU 302, and the thicknessthereof from the first board 320 is greater.

As shown in FIG. 4, a bracket 322 is mounted at the front edge portion12A of the traveling unit supporting section 12 and a front end portionof the left and right paired side portions 12C. The bracket 322 has aninclined face which advances upwardly toward the rear and has a frontend extending forwardly farther than the front edge portion 12A.Further, a pair of fastening pieces 323 are coupled to lower endportions of the first pipe 14A and the second pipe 14B of the drivingunit supporting section 14 and project in a forward direction and indirections in which they approach each other. The first board 320 isfastened to a front end of the bracket 322 and the fastening pieces 323by screws, bolts or the like. The first board 320 is disposed extendingforwardly and backwardly such that the tail wheel PDU 302 is disposed onthe front side while the main wheel PDU 301 is disposed on the rearside. The first board 320 is further disposed in an inclinedrelationship such that it advances upwardly toward the rear. The firstboard 320 is disposed such that a front end portion thereof is displacedrearwardly with respect to a front end portion of the bracket 322. Thefront end portion of the bracket 322 extends forwardly farther than thefirst board 320 and the tail wheel PDU 302 supported on the first board320.

As shown in FIGS. 1 and 3, the converter 304, I/O unit 305 and switchunit 306 are supported on the same face of a second board 325 of therectangular shape. The converter 304 is supported on one side of thesecond board 325 in the longitudinal direction, and the I/O unit 305 andthe switch unit 306 are supported in a juxtaposed relationship with eachother on the other side of the second board 325. The converter 304 isgreater than the I/O unit 305 and is greater in thickness from thesecond board 325. A pair of fastening pieces 326 are coupled to anintermediate portion of an upwardly and downwardly extending portion ofthe first pipe 14A and the second pipe 14B of the driving unitsupporting section 14 and project in directions in which they approacheach other. The second board 325 is fastened to the front side of thefastening pieces 326 and the connection plate 14H by screws, bolts orthe like. The second board 325 has a face directed forwardly andbackwardly and disposed extending upwardly and downwardly. The converter304 is disposed at a lower portion of the front face of the second board325, and the I/O unit 305 is disposed on an upper left portion of thefront face while the switch unit 306 is disposed at an upper rightportion of the front face.

The switch unit 306 has a switch button 328 which extends forwardly,passes through an opening formed in the front face portion of the outershell 18 and is exposed outwardly. An outer face of the switch button328 which is a pushing operation face has a display device 329 which isdirected obliquely upwardly similarly to the outer face of the outershell 18 and emits light in response to an on or off state of theswitch. The display device 329 may be, for example, an LED. It is to benoted that, in another embodiment, the display device 329 may indicate astate of the inverted pendulum type vehicle (for example, presence orabsence of a failure, a battery remaining capacity or the like) in theform of a turning on interval or an emitted light color.

As shown in FIGS. 1 and 2, a first cover 335 is coupled to the frontface side of the first board 320 in such a manner as to cover the tailwheel PDU 302, main wheel PDU 301 and fan 321. The first cover 335 has afront opening 336 at a front end portion thereof and has a rear opening(not shown), which defines an outer periphery of the fan 321, at a rearend portion thereof. In other words, the main wheel PDU 301 and the tailwheel PDU 302 are disposed in a space defined by the first board 320 andthe first cover 335, and the defined space allows communication of airthrough the front opening 336 and the fan 321. The outer shell 18preferably has a vent for communicating the outside and the inside witheach other at a portion thereof which is positioned forwardly of thefront opening 336 of the first cover 335.

A second cover 338 is coupled to the front face side of the second board325 in such a manner as to cover the converter 304, the I/O unit 305 andthe switch unit 306. The second cover 338 is coupled at a lower endportion thereof to the outer face of a rear end portion of the firstcover 335 and communicates with the inside of the first cover 335through the fan 321. The second cover 338 has an upper opening 339 at anupper end portion thereof. In other words, the converter 304, the I/Ounit 305 and the switch unit 306 are disposed in a space defined by thesecond board 325 and the second cover 338, and the defined space allowscommunication of air through the fan 321 and the upper opening 339. Itis to be noted that the switch button 328 of the switch unit 306 extendsthrough the second cover 338 and projects to the front face portion ofthe outer shell 18.

By the configuration described above, if the fan 321 rotates, then airat a lower portion in the outer shell 18 is taken in from the frontopening 336 of the first cover 335, passes in order through the insideof the first cover 335, the fan 321 and the inside of the second cover338 and is discharged from the upper opening 339 of the second cover338. When the air passes the inside of the first cover 335 and thesecond cover 338, it exchanges heat with the tail wheel PDU 302, mainwheel PDU 301, converter 304, I/O unit 305 and switch unit 306 to coolthem. The path defined by the first cover 335 and the second cover 338extends in the upward and downward direction while it is inclined. Sinceair is taken from the front opening 336 disposed on the lower end sideand discharged from the upper opening 339 disposed on the upper endside, the air heated by heat exchange in the first cover 335 and thesecond cover 338 flows easily.

The air discharged from the upper opening 339 of the second cover 338 isintroduced rearwardly in the outer shell 18 along the inner face of theupper wall of the outer shell 18 and is discharged to the outside of theouter shell 18 from an outlet 342 (refer to FIG. 16) formed at an upperend of a rear face portion of the outer shell 18. Therefore, the hightemperature air having passed through the inside of the first cover 335and the inside of the second cover 338 does not hit upon the occupant.It is to be noted that a vent pipe for communicating the upper opening339 and the outlet 342 with each other may be provided in the outershell 18.

The gyro sensor 308 is supported on a bracket 345 (refer to FIG. 4)mounted between front end portions of the paired left and right thirdpipes 14C and is disposed between the lower end portions of the firstpipe 14A and the second pipe 14B as shown in FIG. 1. More particularly,the gyro sensor 308 is disposed between the first board 320 and theright side driving unit 130 in the forward and backward direction anddisposed between the second board 325 and the main wheel 52 in theupward and downward direction.

While, in the electrical unit 300 configured in such a manner asdescribed above, the front edge of the first cover 335 is disposed onthe most front side in the electrical unit 300, as shown in FIG. 1, thefront edge of the first cover 335 is disposed on the rear side withrespect to a vertical line L2 (tangential line) which passes the frontedge of the main wheel 52 (particularly, the front edge of the drivenroller 64 disposed on the most front side) which configures the frontedge of the traveling unit 50. Further, the tail wheel PDU 302, mainwheel PDU 301, converter 304, I/O unit 305, switch unit 306, first cover335 and second cover 338 are disposed rearwardly with respect to avirtual line L3 which passes the front edge of the seat 200(particularly, the front edge of the seat main body 206) and the frontedge of the bracket 322. By such a configuration as just described, if acomparatively large object collides with the front side portion of theinverted pendulum type vehicle 1, then since the object collides withthe front edge of the seat 200 or the front edge of the bracket 322,collision thereof with the electrical unit 300 can be avoided.

In the present embodiment, the vehicle body frame 10 which supports theleft and right driving units 90 and 130 which have a smaller width inthe forward and rearward direction than that of the main wheel 52 isprovided above the traveling unit 50 including the main wheel 52,Further, the electrical unit 300 is provided in the space 315 which is adead space formed by providing the outer shell 18 which smoothly coversthe upper front edge of the vehicle body frame 10 to the front edge ofthe main wheel 52. Consequently, compactification of the entire invertedpendulum type vehicle 1 can be anticipated. Further, since the switchbutton 328 of the switch unit 306 and the display device 329 areprovided on the front side face of the outer shell 18, confirmation ofthe display device and operation of the switch button 328 by theoccupant seated on the seat 200 can be facilitated. Further, it ispossible to make hard an operation of the switch button 328 by a thirdparty other than the occupant.

Now, a configuration and operation of the inverted pendulum type vehicleon which an occupant is to get on is described with reference to FIG.17. When an occupant intends to get on the inverted pendulum typevehicle (namely, to be seated on the seat 200), the occupant wouldoperate a getting-on button 241 (refer to FIG. 17) provided at aposition at which the occupant can easily access the getting-on button241 from the rear of the inverted pendulum type vehicle 1 which is insuch a self-standing state (namely, after starting up) as shown in FIG.1 to temporarily stop the inverted pendulum control. Consequently, asshown in FIG. 17, the vehicle (more particularly, the vehicle body frame10, driving unit supported at the upper portion of the frame 10 and soforth) pivots rearwardly by the self-weight around the hollow axle 54(refer to FIG. 2). Thereafter, the rear side limit stopper 34 providedon the vehicle body frame 10 stops at a position at which it contactswith the upper face of the tail wheel arm 78 to place the vehicle into arearwardly inclined state. At this time, also the seat 200 pivotsrearwardly from the driving position shown in FIG. 1 together with thevehicle body frame 10 to move to a lower getting-on starting position(rearward standby position) shown in FIG. 17. Consequently, since theseat face position of the seat 200 becomes lower, the occupant can beeasily seated even from the rear of the vehicle body. The occupantseated on the vehicle can operate the getting-on button 241 again tostart the inverted pendulum control. The starting of the invertedpendulum control may be executed when predetermined time elapses afterthe seating sensor 307 detects seating of the occupant irrespective ofoperation of the getting-on button 241.

Here, as shown in FIG. 1, the seat main body 206 has a seat face mainportion 206 a including the seat face from the front edge to a centralportion in the substantially horizontal direction as viewed in sideelevation and a seat face rear portion 206 b inclined obliquelyrearwardly upwardly from the rear edge of the seat face main portion 206a. In this manner, since the seat 200 has the inclined seat face rearportion 206 b, the hip of the occupant can be supported in stability. Onthe other hand, when the occupant is seated on the seat 200, since theseat face rear portion 206 b inclines to an approximately horizontaldirection as shown in FIG. 17, the occupant can get on the vehicle moreeasily from the rear of the vehicle body at the rear standby position.Further, in the base member 201 which supports the lower side of theseat main body 206, a main portion 201 a is formed in a substantiallyflat shape and a rear portion 201 b is inclined obliquely rearwardlyupwardly as shown in FIG. 11 similarly to the seat face of the seat mainbody 206. Consequently, the load on the seat face can be dispersedfavorably while permitting deformation of the seat main body 206 by theload of the occupant.

It is to be noted that, when the seat 200 is placed into a rearwardlyinclined state, as shown in the modification of FIG. 18, the seat faceangle may be set such that the seat face rear portion 206 b is placedinto an inclined state same as or lower than the horizontal direction asviewed in side elevation (here, the seat face rear portion 206 b isinclined obliquely rearwardly downwardly by a predetermined angle θ withrespect to the horizontal direction). Consequently, facilitation inseating by the occupant can be enhanced further.

(Posture and Driving Control of the Inverted Pendulum Type Vehicle)

Traveling operation of the inverted pendulum type vehicle 1 isdescribed. The main wheel PDU 301 carries out arithmetic operation atany time regarding a gravity center position of the entire invertedpendulum type vehicle 1 including the occupant who is seated on the seatmain body 206 from variations of the inclination angle and the angularvelocity in the forward or rearward and leftward or rightward directionsof the vehicle body frame 10 measured by the gyro sensor 308.

When the gravity center of the entire inverted pendulum type vehicle 1including the occupant is positioned at a neutral position (for example,a position just above the center of the telescopic strut 180), the mainwheel PDU 301 drives the electric motors 92 and 132 of the left andright driving units 90 and 130 based on a control process in accordancewith the inverted pendulum controlling rule to maintain the vehicle bodyin an uprightly standing posture.

At this time, the tail wheel PDU 302 maintains the electric motor 84 ofthe tail wheel unit 80 in a stopping state based on the control processin accordance with the revolution controlling rule and the tail wheel 82does not rotate.

If the gravity center of the entire inverted pendulum type vehicle 1including the occupant moves to the front side with respect to theneutral position, then, the main wheel PDU 301 drives the electricmotors 92 and 132 of the left and right driving units 90 and 130 in aforward rotational direction at the same speed based on the controlprocess in accordance with the inverted pendulum controlling rule. Theleft and right driving disks 58 rotate forwardly at the same speed inaccordance with the driving of the electric motors 92 and 132, and themain wheel 52 rotates forwardly around the wheel center thereof, namely,revolves in the forward direction. At this time, since a rotationalspeed difference does not occur between the left and right driving disks58, the driving rollers 66 of the driving disk 58 and the driven rollers64 of the main wheel 52 do not rotate and the inverted pendulum typevehicle 1 moves straightly forwardly.

If the gravity center of the entire inverted pendulum type vehicle 1including the occupant moves to the rear side with respect to theneutral position, then the main wheel PDU 301 drives the electric motors92 and 132 of the left and right driving units 90 and 130 in the reverserotational direction at the same speed based on the control process inaccordance with the inverted pendulum controlling rule. The left andright driving disks 58 rotate reversely at the same speed in accordancewith the driving of the electric motors 92 and 132, and the main wheel52 rotates reversely around the wheel center thereof, namely, revolvesin the rearward direction. At this time, since a rotational speeddifference does not occur between the left and right driving disks 58,the driving rollers 66 of the driving disks 58 and the driven rollers 64of the main wheel 52 do not rotate and the inverted pendulum typevehicle 1 moves straightly backwardly.

Upon forward movement and backward movement, the tail wheel PDU 302carries out the control process in accordance with the revolutioncontrolling rule to maintain the stopping state of the electric motor 84of the tail wheel unit 80, and consequently, the tail wheel 82 does notrevolve. However, the free rollers of the tail wheel 82 rotate togetherwith the forward movement of the inverted pendulum type vehicle 1.

If the gravity center of the entire inverted pendulum type vehicle 1including the occupant moves to the left side or the right side withrespect to the neutral position, then, the main wheel PDU 301 drives theelectric motors 92 and 132 of the left and right driving units 90 and130 in rotational directions and/or at rotational speeds different fromeach other based on the control process in accordance with the invertedpendulum controlling rule. By the driving of the electric motors 92 and132, a rotational speed difference occurs between the left and rightdriving disks 58. Consequently, a component of force in a directionorthogonal to force in a circumferential (tangential) direction by therotating force of the left and right driving disks 58 acts uponcontacting faces of the left and right driving rollers 66 and the drivenrollers 64 of the main wheel 52. By the component of force, the drivenrollers 64 rotate (revolve) around the central axial line thereof.

The rotation of the driven rollers 64 is determined by the rotationalspeed difference between the left and right driving disks 58. Forexample, if the left and right driving disks 58 are rotated in reversedirections different from each other at the same speed, then the mainwheel 52 does not revolve at all but rotation of the driven rollers 64occurs. Consequently, the driving force in the leftward or rightwarddirection is applied to the main wheel 52 and the inverted pendulum typevehicle 1 moves (moves abeam) in the leftward or rightward direction.Further, if the left and right driving disks 58 are rotated at speedsdifferent from each other in the same direction, then rotation of thedriven rollers 64 occurs together with the revolution of the main wheel52. Consequently, the inverted pendulum type vehicle 1 moves obliquelyforwardly or obliquely rearwardly.

At this time, the tail wheel PDU 302 may drive the electric motor 84 ofthe tail wheel unit 80 so that the tail wheel 82 rotates (revolves) at arotational speed equal to a moving speed in an abeam direction based onthe control process in accordance with the revolution controlling rule.If a difference occurs between the movement amount by rotation of thedriven rollers 64 of the main wheel 52 and the movement amount byrotation of the tail wheel 82, then the inverted pendulum type vehicle 1turns.

While the present invention has been described in connection with anumber of illustrative embodiments thereof, as can be easily understoodby a person skilled in the art, the present invention is not limited tosuch an embodiment as described above but can be suitably alteredwithout departing from the scope of the present invention. For example,the main wheel 52 may be configured such that a plural number of drivenrollers 64 are combined so as to form a ring shape in which they canrotate independent of each other. The supporting member for the drivenrollers 64 by such a combination as just described is not limited to thecircular ring member 62, but may be implemented by a disk-shaped memberhaving a plurality of supporting portions for the driven rollers 64 onthe outer periphery thereof. Further, the tail wheel 82 is not limitedto an omnidirectional wheel but may be implemented by a main wheel usinga normal rubber tire. The projecting portion 102A of the reduction gear96 of the left side driving unit 90 may project to the vehicle body rearside with respect to the position of the central axial line of theelectric motor 92 reversely to the projecting direction of theprojecting portion 142A of the reduction gear 136 of the right sidedriving unit 130. The left side driving unit attachment plate 22 and theright side driving unit attachment plate 24 may have openings(through-holes) through which the reduction gear output power shafts 98and 138 can penetrate in place of the cutaway portions 22B and 24B.

Further, the components in the embodiments described above are notnecessarily essentially required components, but can be suitably chosenand selected without departing from the scope of the present invention.The reduction gear is not essentially required but may be omitted, butthe left and right driving pulleys 100 and 140 may be directly driven bythe left and right electric motors 92 and 132 as shown in FIG. 19. Alsothe tail wheel unit 80 may be omitted.

DESCRIPTION OF REFERENCE SYMBOLS

-   -   1 . . . Inverted pendulum type vehicle, 10 . . . Vehicle body        frame, 12 . . . Traveling unit supporting section, 14 . . .        Driving unit supporting section, 16 . . . Battery supporting        section, 18 . . . Outer shell, 22 . . . Left side driving unit        attachment plate, 22A . . . Bolt penetrating hole, 22B . . .        Cutaway portion, 24 . . . Right side driving unit attachment        plate, 24A . . . Bolt penetrating hole, 24B . . . Cutaway        portion, 26 . . . Attachment bolt, 28 . . . Mounting bolt, 40 .        . . Step, 42 . . . Front side limit stopper, 44 . . . Center        post, 46 . . . Gusset, 47 . . . Cylindrical bush, 50 . . .        Traveling unit, 52 . . . Main wheel, 54 . . . Hollow axle, 54A .        . . Positioning stepped portion, 55 . . . Central through-hole,        56 . . . Ball bearing, 58 . . . Driving disk, 60 . . . Driven        pulley, 62 . . . Circular ring member, 64 . . . Driven roller,        66 . . . Driving roller, 68 . . . Nut, 68A . . . Ring-shaped        protrusion, 72 . . . Headed bolt, 74 . . . Nut, 78 . . . Tail        wheel arm, 80 . . . Tail wheel unit, 82 . . . Tail wheel, 84 . .        . Electric motor, 85 . . . Outer shell, 90 . . . Left side        driving unit, 92 . . . Electric motor, 94 . . . Output power        shaft (motor output power shaft), 96 . . . Reduction gear, 98 .        . . Output power shaft (reduction gear output power shaft), 100        . . . Driving pulley, 102 . . . Gear box, 102A . . . Projecting        portion, 122 . . . Cog belt, 124 . . . Adjustment bolt, 126 . .        . Lock nut, 130 . . . Right side driving unit, 132 . . .        Electric motor, 136 . . . Reduction gear, 138 . . . Output power        shaft (reduction gear output power shaft), 140 . . . Driving        pulley, 142 . . . Gear box, 142A . . . Projecting portion, 144 .        . . Cog belt, 146 . . . Adjustment bolt, 148 . . . Lock nut, 170        . . . Seat unit, 180 . . . Telescopic strut, 181 . . . Unlocking        button, 182 . . . Piston rod, 184 . . . Cylinder tube, 198 . . .        Seat lifting lever, 200 . . . Seat, 201 . . . Base member, 202 .        . . Seat frame, 204 . . . Seat bottom cover, 206 . . . Seat main        body, 206 a . . . Seat face main portion, 206 b . . . Seat face        rear portion, 207 . . . Side guard member, 211 . . . Main frame,        212 . . . Sub frame, 221 . . . Lever arm, 222 . . . Operation        arm, 222 a . . . Engaging portion, 234 . . . Pushdown rod, 235 .        . . Pivotal motion restricting pin, 236 . . . Opening, 241 . . .        Getting-on button, 250 . . . Battery pack, 251 . . . Battery        case, 254 . . . Front side wall, 257 . . . Opening, 260 . . .        Lid, 262 . . . Locking protrusion, 263 . . . Accepting hole, 268        . . . Arm, 270 . . . Latch hole, 273 . . . Latch, 300 . . .        Electrical unit, 301 . . . Main wheel controlling power drive        unit, 302 . . . Tail wheel controlling power drive unit, 304 . .        . DC-DC converter, 305 . . . I/O interface unit, 306 . . .        Switch unit, 308 . . . Gyro sensor, 320 . . . First board, 321 .        . . Fan, 325 . . . Second board, 328 . . . Switch button, 329 .        . . Display device, 335 . . . First cover, 338 . . . Second        cover

We claim:
 1. An inverted pendulum type vehicle comprising: a vehiclebody frame; a main wheel formed by combining a plurality of rotatabledriven rollers such that axial lines of rotation of the driven rollersform a ring; left and right driving disks supported for rotation on thevehicle body frame in such a manner as to be positioned on the oppositeleft and right sides of the vehicle body frame in a substantiallycoaxial relationship with an axial line of rotation of the main wheeland each including a plurality of rotatable driving rollers disposed forcontact in a twisted relationship with the driven rollers; left andright driven pulleys provided coaxially on the vehicle body outer sidesof the driving disks; left and right driving units attached to thevehicle body frame above the main wheel and having output power shaftsto which driving pulleys are attached; and endless transmission membersextending between and around mutually corresponding ones of the drivingpulleys and the driven pulleys, wherein the left and right driving unitsare disposed in an upwardly and downwardly offset relationship from eachother.
 2. The inverted pendulum type vehicle according to claim 1,wherein the left and right driving units overlap at least at partthereof with each other as viewed in top plan view.
 3. The invertedpendulum type vehicle according to claim 1, wherein each of the drivingunits comprises an electric motor and a reduction gear disposed betweenthe electric motor and a corresponding one of the output power shafts.4. The inverted pendulum type vehicle according to claim 2, wherein eachof the driving units comprises an electric motor and a reduction geardisposed between the electric motor and a corresponding one of theoutput power shafts.
 5. The inverted pendulum type vehicle according toclaim 3, wherein the electric motor of each of the driving units isdisposed at a position displaced to the side on which the correspondingone of the reduction gears is not disposed with respect to a center linein the vehicle widthwise direction, and the electric motor of a drivingunit disposed on an upper stage is positioned just above the reductiongear of a driving unit disposed on a lower stage, while the reductiongear of the driving unit disposed on the upper stage is positioned justabove the electric motor of the driving mechanism unit disposed on thelower stage.
 6. The inverted pendulum type vehicle according to claim 3,wherein each of the reduction gears comprises a projecting portion,projecting sideways with respect to a center axial line of acorresponding one of the electric motors, and the projecting portions ofthe reduction gears are disposed so as to project in differentdirections from each other between the left and right driving units. 7.The inverted pendulum type vehicle according to claim 5, wherein each ofthe reduction gears comprises a projecting portion, projecting sidewayswith respect to a center axial line of a corresponding one of theelectric motors, and the projecting portions of the reduction gears aredisposed so as to project in different directions from each otherbetween the left and right driving units.
 8. The inverted pendulum typevehicle according to claim 1, wherein the vehicle body frame has a pairof left and right attachment plates disposed substantially parallel toeach other on the opposite sides of the vehicle body, the attachmentplates having openings formed therein through which the respectiveoutput power shafts extend.
 9. The inverted pendulum type vehicleaccording to claim 2, wherein the vehicle body frame has a pair of leftand right attachment plates disposed substantially parallel to eachother on the opposite sides of the vehicle body, the attachment plateshaving openings formed therein through which the respective output powershafts extend.
 10. The inverted pendulum type vehicle according to claim3, wherein the vehicle body frame has a pair of left and rightattachment plates disposed substantially parallel to each other on theopposite sides of the vehicle body, the attachment plates havingopenings formed therein through which the respective output power shaftsextend.
 11. The inverted pendulum type vehicle according to claim 5,wherein the vehicle body frame has a pair of left and right attachmentplates disposed substantially parallel to each other on the oppositesides of the vehicle body, the attachment plates having openings formedtherein through which the respective output power shafts extend.
 12. Theinverted pendulum type vehicle according to claim 6, wherein the vehiclebody frame has a pair of left and right attachment plates disposedsubstantially parallel to each other on the opposite sides of thevehicle body, the attachment plates having openings formed thereinthrough which the respective output power shafts extend.
 13. An invertedpendulum type vehicle comprising: a vehicle body frame; a main wheelformed by combining a plurality of rotatable driven rollers such thataxial lines of rotation of the driven rollers form a ring; left andright driving disks supported for rotation on the vehicle body frame insuch a manner as to be positioned on the opposite left and right sidesof the vehicle body frame in a substantially coaxial relationship withan axial line of rotation of the main wheel and each including aplurality of rotatable driving rollers disposed for contact in a twistedrelationship with the driven rollers; left and right driven pulleysprovided coaxially on the vehicle body outer sides of the driving disks;left and right driving units attached to the vehicle body frame abovethe main wheel and having output power shafts to which driving pulleysare attached; and endless transmission members extending between andaround mutually corresponding ones of the driving pulleys and the drivenpulleys, wherein the inverted pendulum type vehicle has an adjustableattachment mechanism for attaching the left and right driving units tothe vehicle body frame, such that positions of the left and rightdriving units in the upward and downward direction can be adjustablychanged.
 14. The inverted pendulum type vehicle according to claim 13,wherein the inverted pendulum type vehicle has adjustment bolts attachedfor rotation to the vehicle body frame and screwed with an upper portionof the driving units, and the driving units are movable in the upwardand downward directions with respect to the vehicle body frame byadjustment of the adjustment bolts.
 15. The inverted pendulum typevehicle according to claim 13, wherein attachment plates are attached tothe vehicle body frame at side portions of the vehicle body, and boltpenetrating holes, each elongated in an upward and downward direction,are formed in the attachment plates, and the driving units are fixed tothe vehicle body frame by mounting bolts which extend through the boltpenetrating holes and are held in threaded engagement with the drivingunits.
 16. The inverted pendulum type vehicle according to claim 15,wherein openings through which the output power shafts extend are formedin the attachment plates, respectively, and portions of the drivingunits which neighbor with the output power shafts are fixed to theattachment plates.
 17. The inverted pendulum type vehicle according toclaim 15, wherein the attachment plate of the left side driving unit andthe attachment plate of the right side driving unit are respectivelyattached to the corresponding left and right sides of the vehicle body.18. The inverted pendulum type vehicle according to claim 14, whereinthe left and right driving units are disposed in an offset relationshipfrom each other on upper and lower stages, respectively, and wherein anupper frame portion of the vehicle body frame, to which the driving uniton the lower stage is attached, is positioned below the driving unit onthe upper stage, and a space for receiving a tool for rotating theadjustment bolt is maintained between the upper frame and a bottomportion of the driving unit on the upper stage, even when the drivingunit on the upper stage is positioned at a most downward positionthereof.
 19. The inverted pendulum type vehicle according to claim 15,wherein the left and right driving units are disposed in an offsetrelationship from each other on upper and lower stages, respectively,and wherein an upper frame portion of the vehicle body frame, to whichthe driving unit on the lower stage is attached, is positioned below thedriving unit on the upper stage, and a space for receiving a tool forrotating the adjustment bolt is maintained between the upper frame and abottom portion of the driving unit on the upper stage, even when thedriving unit on the upper stage is positioned at a most downwardposition thereof.
 20. The inverted pendulum type vehicle according toclaim 15, wherein each of the left and right driving unit comprises anelectric motor and a reduction gear, and wherein the reduction gears arefixed to the respective attachment plates, while the electric motors arepositioned on the open side.